How to deal with severe mental fatigue without taking time off?

Question

I work as a remote software developer. I work on a casual basis from home, and I'm free to work as much or as little for my boss as I like, while billing my boss on a weekly basis for the worked time using a time-sheet.

Recently I got very excited about a private project of mine, and over-worked myself for a few months on said private project (unpaid), while only investing a necessary amount of hours into my paid employment. I was literally working all my waking hours, without taking weekends or breaks. I only introduced short-but-intensive gym sessions at some point to maintain basic physical health. My boss is/was fine with this.

Now I'm trying to invest a "normal" amount of hours (20-40) into my paid employment again, but, unexpectedly, I find that I just cannot. My mind refuses to cooperate, fights back, and clamps to any brainless distraction it can find. I start working (programming) but it is only a matter of minutes until I find myself distracted by something else, and have to remove the unproductive time from the time-sheet. I can hardly accumulate one or two hours of work sitting in front of the computer the whole day. This has been going on for a few weeks now. My sleep patterns are also out-of-whack due to working during the night.

I've done some research, and it appears that this kind of "burnout" (mental fatigue) is a known phenomenon among programmers. Usually, the solution includes taking time off. This is not really an option for me, since I have burned any financial cushion due to the work on my private project. What steps can I take to restore my productivity, including ways to approach my friendly boss about it?

Answer 1

If you're experiencing burnout (i.e. this is affecting your health, your general mental state, your social life or other parts of your life), go see a doctor. Burnout is serious and can result in long-term damage unless treated appropriately. The below should not be considered alternatives to getting professional medical treatment.

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Many of the points below are important to prevent burnout or deal with mental fatigue, but they can also help improve productivity (and happiness) in general.

I would recommend trying some or all of these things, even if not doing them has never been a problem before. Suffering from mental fatigue isn't exactly normal circumstances.

As quite excellently noted by the author of the question in a comment:

This serves as a great checklist-style starting point for a plan of lifestyle change. Primarily, it is a prompter for numerous reasonable considerations that may (or may not) contribute to the mental fatigue. It is then in the reader's hand to reach his own conclusions about what applies to him, what of the advice to take, and what lifestyle-changes to pursue. Implicitly, none of this replaces medical attention or treatment - if the same is required, it is again up to the reader's discretion to seek it.

Exercise, Socialise, Maintain a healthy diet

While any given person may not much like or see the value in any or all of these things, they're hugely important to general mental health.

I'm no expert, but I would recommend, at the very least:

• Exercising twice a week for at least 30 minutes.
• Taking at least a 10-20 minute walk every day (the fresh air and sunlight helps a lot too).
• Speaking to another human being every day (in person, ideally, about anything; I wouldn't count instant message or text chat here). I realise this may be hard if you live alone and work from home, but I would recommend it especially strongly in that case.
• Going out with friends once a week.
• Treating yourself to a tasty snack or meal out once a week. This is more optional than the rest. It's partly for the pleasure and partly to make it easier to eat healthy the rest of the time.

Sleep better

If you're not sleeping well, the resulting exhaustion can, by itself, make it hard to concentrate and get things done.

There are plenty of resources online addressing this, so I wouldn't go into too much detail on any of the recommendations nor try to provide an exhaustive list of recommendations.

Some things to try to do:

• Get 8 hours of sleep
• Go to bed well before midnight (combined with the above, this means: sleep when the sun's not shining)
• Go to bed and wake up at the same time every day (even on weekends)
• Don't snooze your alarms in the morning
• Sleep in a dark room (especially try to avoid lights from screens or LED's, which may include notifications you get at night on your phone)
• Avoid screens before bed or after it gets dark or install a blue light filter on your computer and phone like Flux or Twilight
• If you can't fall asleep after a while, get up and do something for a while - don't spend hours laying in bed awake
• Get lots of sunlight when you're awake (to help with your circadian rhythm, among other benefits)
• Avoid sleeping pills (unless prescribed by a doctor). Taking too many of these might make you dependent on them and make them less effective.
• Cut down on caffeine and sugar, especially in the afternoon and evening.

Relax, in healthy ways

Everyone needs to relax occasionally, so it's worth making a conscious effort to do things to relax and taking a sceptical look at anything you do to relax.

Although what any given person finds relaxing will vary greatly from one person to the next.

Exercising and socialising (especially doing sports, mentioned above) may be a sufficient source of relaxation for some, but it's not that relaxing for everyone.

If you have a hobby that's the same as your day job, you may need something other than this to truly relax.

If your day job requires a lot of complex problem solving, you may need to give your brain a break and not try to relax with something where you need to think a lot like Sudoku or chess.

Social media (including Stack Exchange and YouTube) is a topic all by itself. While I'd hesitate to say it's destructive to everyone, plenty of people quit social media because it has a negative effect on their mental health. They're optimised to keep you on the site as long as possible at any cost, not to be a good way to relax. So that's certainly something to keep in mind if you use this to relax, especially if you try to do so during a work day, have a hard time putting it down or don't feel all that satisfied afterwards.

Video games is something one can also say a lot about, and a lot of what I wrote about social media also applies to them. The free-to-play / mobile variety (which you can play for "just 5 minutes") are especially noteworthy, because they're optimised to keep you playing moment to moment, with daily rewards "forcing" you to come back and keep playing, potentially turning it into more of an obligation than a way to relax.

(Free-to-play) video games and social media both generally mess with dopamine production (your body's "feel good" drug). This could potentially have a long-term effect on how enjoyable you find anything.

Working from home might be a problem

When working from home, it can be hard to mentally separate work and play. Having where you work be in a different physical place can help with this.

If your employer doesn't have a physical office where you can work, you could also consider a coworking space. Or perhaps you have a room you can use exclusively for work.

You might also want to read through: How do you separate or integrate your work and home life when telecommuting?

Work reasonable hours

While not really applicable to you now, it may apply to others also suffering from similar symptoms.

Working more than 8 hours a day or not taking weekends off for extended periods of time may be one of the primary causes of burnout. One wouldn't really be able to fix burnout or mental fatigue if what's causing it is still there.

Follow a plan, routine or schedule

Our brains are (generally) good at doing this.

When you work from home, you may not have a well-defined start and end of the day. If you don't, I would recommend you define what time you start working, what time you take lunch, for how long and what time you stop working, and stick to this.

You could also set up a plan for what you'll achieve on some specific day and for how you structure your day.

If necessary, you could define how long you'll work before taking a break, what you'll do during that break and how long that break will be (set a timer for both). Many people swear by this to maximise their productivity.

Breaks should include avoiding screens altogether for at the very least 10 minutes every hour (for eye health, but also because things on electronic devices tend not to make for the best breaks - see also what I wrote about relaxing above), and regularly going outside.

When working normally, some recommend breaks after only about 30 minutes (and you may be surprised what you can get done in that time), while others might recommend working up to an hour. Recommended breaks are typically between 5 minutes (with longer breaks later on) and 30 minutes. One popular technique is the Pomodoro technique and there are a number of apps to make this easy. Another option would be to say you'll finish this one or two things before taking a break (as long as that won't take too long). I would recommend experimenting and further reading up on this to find the best solution for you.

To get back to being productive with mental fatigue or burnout, I might recommend tending towards shorter working periods and longer breaks, to give your brain more time to recover.

Avoid distractions

This also relates to some of the points above (especially working from home).

Getting constant alerts for instant messages or emails or having instant access to anything on your computer you usually use for relaxing could make it quite hard to focus.

Some options to consider:

• Turn off notifications for phone apps, IMs and/or emails and only check these intermittently or at certain times of the day.

  If you don't want to disable them completely, some apps may have notifications less invasive than a huge popup, like a change to the icon or title in the taskbar.

  Your phone may also have some options to make some or all notifications less invasive, without disabling them completely (like disabling sounds or vibration or not even switching on the screen and only showing the notification light).

• Install an app or browser extension to prevent opening certain apps or websites during certain hours.

• Uninstall certain apps altogether.
• Get a dedicated work computer (possibly sponsored by your employer). It would be much easier to avoid opening up some app if it's not even installed on the computer you're working on.

Don't self-medicate

While certain medications might help or even be necessary to fix the problem, I would not recommend taking these without consulting a doctor first.

Medication carries serious risks: they may have serious side-effects, have a risk of overdosing, create a dependency on the drug, become less effective with overuse or cause damage in long-term. A doctor would help you minimise, deal with or avoid these risks.

Take on easier work tasks for a while

If there are tasks that need doing but don't require much concentration or time per task, you could consider focusing on these for a few days. Or at least for part of the day.

But do actually fully focus on these tasks like you would with "regular" work. Don't just do it for 5 minutes, get distracted and do something else, get back to it for 5 minutes, etc. That wouldn't help much.

This would allow you to get back into the spirit of working normally even if you can't really focus on anything. Once you're used to normal working hours again, focusing during that time should be much easier.

Give it time

Don't expect to immediately get back to 100% productivity. It may take a few weeks.

Take time off

You say this is not really an option, but I include it anyway for completeness and because it's one of the best ways to deal with mental fatigue (and you don't necessarily have to take a large amount of time off). Although one should still address any other potential contributors mentioned above.

Taking at least some time off away from home might be a lot more effective than just staying at home.

Even just taking a trip somewhere over a long weekend could help a lot.

I would especially recommend something that actually gets you excited to think about and something you'd typically really look forward to. Taking time off to be bored at home could do more harm than good.

Also, if you can currently only get one or two hours of productivity a day and taking a few days or a week off would fix your problem, that would definitely be worth it, even just from a purely financial perspective.

If applicable: I think debt is often harmful and ruins lives, but in this case I'd consider taking (or adding) a bit of debt so you can take time off now, because your mental health is one of the most important things in life and this could make financial sense even in the short term. But I would recommend a lot of care here and a very detailed plan of when you're going to pay it back.

See a doctor

If it isn't a financial burden, I would recommend regularly speaking to a therapist even if nothing is specifically wrong.

Although if work productivity is the only problem and it hasn't been a problem too long, I might not say it's specifically necessary. I would expect it to take some time for your brain to adjust after such significant shifts in how you spend your time. A few weeks is probably a bit long, but not if you haven't been doing much of the above.

If you need a doctor's note to take paid medical leave, you might want to go see a doctor anyway.

I should note there is no wonder drug to fix this. A (good) general practitioner or therapist would likely do some combination of recommending what I wrote above, although they may be more methodical about it, looking for other medical causes and supplementing treatment with medication to get results faster. A bad doctor might just prescribe sleeping pills and Adderall to deal with the problem in the short term without trying to address the cause or considering the long-term effects of those drugs.

How do you talk to your boss about it?

The first consideration would be the purpose of talking to them.

If they've probably seen your lack of productivity or raised concerns about it, this could be a decent way to address that. I'd probably recommend just keeping it simple:

• Say you've been having a hard time concentrating lately
• Give a reason (otherwise they may think it's because you dislike the job): you've overworked yourself on a personal project, which you've stopped doing now (but concentration is still a problem).
• Point out what they probably know already: the number of hours you've logged or anything else they may have noticed.
• Explain how you're addressing it: give a summary from the above points applicable to you, but avoid going into too much detail or anything that would be too personal. It would also be helpful if you can say you're seeing a doctor about it.

They may specifically ask about or recommend taking leave, so you should be prepared to answer that. I wouldn't get into your financial situation, but you can potentially say it's not the best time for you to take leave now and you plan to take some as soon as you're able.

If you want to take time off (medical or regular leave), it might also be useful to discuss it to justify the leave. Although it may not be necessary (you should not have to justify regular leave and a doctor's note should be sufficient for medical leave) and you should probably judge whether to do this based on how nice your boss is.

In other cases, I wouldn't discuss it unless you typical discuss personal matters with your boss.

Answer 2

Go talk to a doctor or psychologist. Apart form this advice, do not listen to people on the internet saying things you should do

Burnout is a serious affliction, not to be taken lightly.Your brain is overworked and things have broken down. This does not need to be permanent but it could be if you do not take care. That is not to say you have the full version but it is worth considering.

Treat this like any part of your body that was overworked and is now broken.

I specifically did not answer your question about approaching your boss because that strategy is completely dependent on your conversation with a doctor. They should be able to give you a noncommittal doctor's note with which to take the necessary further steps.

Edit: The above answer is written through the lens for who primary healthcare is easily available and free(ish). I'm not from the US so for me this is not a desperate or illogical measure. If this is not the case some of the more self-help oriented answers might be for you.

Answer 3

While you might actually suffer from a burn-out, you might have been wrong with your self-diagnosis.

Ideally, you go away from programming, in a relaxing environment, for a minimum of two weeks. You define relaxing: walking in nature, seaside, doing some sports - hiking, cycling...

But you state you do not want to take time off. In this case, we need to redefine the relaxation.

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Decide the minimum needed work, to maintain the job and the current life-style. Decide the maximum amount of work you want to do - of course, it should be as little as possible during the recovery.

While working, take short breaks (10-15 min every 1 hour) and move away from the computer. If possible focus your vision on "infinity": watch the sky, a distant forest, distant buildings... Do NOT read anything (computer, smartphone, books, magazines...). Your eyes need relaxation too, and they are too closely liked to the brain.

In your free time, combine passive rest (sleeping, walking in green areas...) with active rest (doing some sports of your choice). One big effect of doing sports is that your brain will have an additional "delivery" of oxygen and nutrients - helping the recovery.

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A topic quite often overlooked is food. Concentrate mostly on fresh, intensely colored vegetables and fruits. They will bring you a huge amount of vitamins, fibers, antioxidants, minerals etc., all of them essential in your recovery. Heat-cooking destroys some of the nutrients, so it is important that you maximize (to the extent possible) the intake raw food.

Intensely colored fresh food: green (spinach, broccoli, lettuce, parsley leaves - any leaves actually), yellow (lemons, bananas), orange (oranges & co., some berries, carrots), black / dark blue (several berries), red (cherries, some berries, beet roots). The list can continue. Avoid fast food of any kind, as much as practically possible.

The diet suggested is especially important if you are a "typical" programmer, living on pizza and coke / coffee.

Answer 4

Speaking as someone who also works from home as a software engineer, and who also loves his hobby projects, I can suggest some low impact things that might help provided you have not got yourself in too deep.

Take a short break soon

Whatever you can afford, perhaps a long weekend. Do something you would not usually do, for a change. If you are low on money, just stay at home, visit friends, go shopping, do some gardening, or even just clean the house thoroughly - pick activities that break from your current routine. Importantly, no screen, keyboard, TV or gaming time.

Establish a rough daily and weekly routine for work days

Working from home can get chaotic without some discipline. In part that can seem attractive as you "work where you want, when you want", but it can get out of hand easily. Little routines and minor habits/rituals that end with you ready to work at a set time and environment can help get over minor blocks.

As you have probably fallen out of these habits, re-establish them. Don't over-think it, and the routine should not be over-ambitious or challenging (it's not yet another project) but you will need to start by setting youself specific targets.

For me, I have a few set morning routines that change depending on need, but most of them involve leaving the house, and returning to it in time and ready to work. For instance, plan to get up before 8:00, go shopping for any daily supplies at a local shop, have a coffee/breakfast, and be ready to start the day's work at 9:30. But really these can be anything, as long as you set yourself a few very basic simple tasks unrelated to work.

Again, it helps if you avoid including screen or keyboard time amongst the routine. It's OK if you want to check emails/social media etc . . . but don't think of that as part of the routine - it's something to do in addition if you are ahead of schedule on your routine.

Commit yourself to sustainable work practices within your comfort zone

Even if the money is tight, setting youself a mental goal of "doing as much work as possible", or "I must make up for lost time" will be self-defeating.

If you are only charging for "productive time", perhaps a goal of 6 hours a day is already quite ambitious. At least initially. Again, if that involves you taking a 2 hour lunch break, don't use that time to pick up some hobby code. Take a stroll, read a book, or take the time to fix yourself a (healthy) cooked lunch instead of just a sandwich.

When you feel low on energy, first thing to drop is the hobby work

The professional work is what allows you to afford to even have your lifestyle and think of doing the hobby work. Hobby work needs to be kept as a distinct second-place goal, and you can think of your priorities simply:

• Your own health and mental well-being. This is where the other answers are coming from telling you to seek medical help. If you decide to try this answer first, but cannot self-help your way out of inability to work in a few days, and still feel burnt out, then you should reconsider the other answers.

• Your financial well-being. The professional work pays the bills. Try to commit to a minimal amount of paid work continuously and not let it drop as far as you did recently such that your finances hit a low point. Bear in mind that poor finance may be forced upon you, so don't use your savings or "disaster buffer" money to fund hobby work that you are excited about - if that's still a thing for you, ensure you have money set aside specifically for that next time around.

• Fun stuff. Whatever it may be.

Of course a little fun is important for your well-being, and feeling healthy will help you work, so it is not really as clear cut as above. However, it may help to think of your hobby programming as purely fun, a "luxury" that you need a little overhead for in both the other priorities before you put significant time into it again.

Answer 5

You should consider speaking with your doctor regarding your fatigue.

Since you're now working more "normal" hours, you should be getting back to a good sleeping pattern, so some sleeping tablets might help get your body-clock back on track and give your mind the rest that it needs. Obviously though, discuss your need for restful sleep with your doctor so that you can be prescribed appropriately.

Fresh air is also a good relaxant. If you have a dog, walk it. If you don't have a dog, pretend that you do and get out every evening (or even before work) and spend 20-30 minutes just walking. I do this (although I have dogs), and walking is a fantastic way of letting your mind relax. Yes, I do think about things while I'm walking, but it's a healthy, positive form of mulling things over.

Answer 6

The answer may not be as complicated as people make out. Simply this: stop working on your personal project. Just put it away and focus instead fully on your paid work. At the same time, develop a habit of working regular hours, and using your non-working hours for self-fulfillment, for example, doing things that don't require a lot of mental effort, like going out for dinner, reading a novel (not a technical book!), watching a movie, or hanging out with friends. Develop regular sleep hours. Just be normal for a while and don't try to conquer the world. In other words, put your life in order. Simplify.

Answer 7

What worked for me: get a job in an office. I also spent about 5 years working from home, sometimes on multiple projects at once and also found myself unable to force myself to concentrate anymore. I started to wonder whether I will be ever productive and employable again.

But then I started a new gig, which required office presence. Getting a new job/project is exciting enough to give a lot of energy and motivation. I found that, even if I am not as productive as I was in my twenties, I am still better than many. Also I do not have to remove anytime from my timesheet anymore, since I am in the office! Yes, sometimes I feel longing for those years when I was working in pijamas at 3 AM, but regular working hours have their benefit, especially for the sleep pattern.

Answer 8

I'm going to contribute simply with something that worked well for me in a similar situation. It may be entirely unsuitable for you, and you may be better off consulting with a professional as many answers here have suggested.

Just take the time off. Do something that will generate value, but nothing that requires staying in a room staring at a computer. Personally I spent two weeks landscaping my garden. Got a cheap secondhand rotovator, stripped everything back to bare earth and removed every stone. I planted trees, rolled out turf, weeded, turned over soil, built walls and blistered my hands. I slept perfectly every night, and I felt happy that my endeavours were producing something worthwhile in the longer term. This wasn't wasted time, it was investment in my own mental health, my environment, and the place I lived.

You think you can't take the time off and you have no financial cushion, but you need this. Sell something, borrow from family on a short term, make a plan that allows you look after yourself first and worry about earning once you're back at full strength. A fried developer is no good to anyone, and anyone who relies on your skills will understand the requirement for some personal time. You can make it happen.

Answer 9

As a fellow Developer, I have been where you are. These help:

1. Watch your caffeine intake! Too much coffee/tea messes with your head; revs it into high gear, and causes your mind to “refuse to cooperate.” It also disrupts your sleep cycles. It’s a vicious cycle: you are exhausted, so you drink coffee, which interrupts your sleep, and you wake up exhausted, so you drink more coffee... I found that going cold turkey—no coffee—helped a lot. You will be amazed at the grip that caffeine can have.
2. Eat healthy. Even quick simple meals like vegetable stir-fry and omelettes are far better than fast food.
3. Start each day with a quick 15-minute walk around the block. Keep your “morning walk” clothes in one spot, so you’re not groggily stumbling around in the dark looking for socks when the clock is ticking.

This is a precursor to health problems.

Personally, I had to take time off when burned out like this.

Ultimately you have to set boundaries with your work.

Answer 10

This could be me.... several times throughout my career.

What I can recommend from personal experience in a situation like that is:

• productive distraction
• conscious time scheduling
• intense relaxation

Productive Distraction

Your mind wanders and no amount of willpower will force it on track, because willpower is the exact resource that you've spent all of. But you can gently nudge it towards productive tasks that provide the distraction it seeks.

Many people have these tales of cleaning the house when an important deadline was looming. Your mind doesn't want to tackle your programming work because it's just had enough of that. Other tasks that it also doesn't want, that you've been pushing out, now seem more attractive in comparison. Do the things that have been on the todo-list for a month or a year already. Staring at a screen or finally cleaning up the basement, which is more productive?

This will give you the feeling that you've accomplished something and make you feel good about yourself instead of bashing yourself for being unproductive. It will relax your brain from the activity it currently hates, and give you back a bit of energy.

Conscious Time Scheduling

Google Pomodoro Technique, or similar systems, then schedule your time accordingly. Instead of sitting down without a plan (except the general "let's work"), intentionally include time for relaxing, surfing YouTube or whatever your distractions are. Plan 25 minutes of work, 5 minutes of pure relaxation (drink a tea or something), then 25 minutes of YouTube, then 5 minutes of toilet break, then 25 minutes of work... or whatever schedule you think works for you. Include just a little bit more work time than you currently manage - small steps.

Now here's the reverse psychology trick: Do not work more than 25 minutes, even if you feel like you want to. The time you schedule is both the lower and the upper limit. Stick to it exactly.

This will train your brain to accept the time schedule (it will take a couple days until you notice and stop to struggle against it) and it will satisfy the monkey brain because the next YouTube, Facebook, or whatever, session is coming right up if only it can wait a bit (it hates waiting, but if it knows the fun part will come, that makes it easier).

It takes a lot of effort to stick to your schedule when you're down on energy. Start with planning half your day strictly and to heck with the other half because anyways you're not productive. But you will see an increase in billable time within a few days.

Intense Relaxation

The most tricky and personal. We tend to relax on YouTube and Facebook or whatever because those commercial services are fine-tuned by psychologists to create the impression that they're pleasurable. But they don't actually relax the brain.

Find a few things that actually are relaxing to you. The things that you sometimes have to force yourself to do, but you almost always make you feel better in the end. Maybe meeting with friends, or going to a live music show, or watching a movie, or taking a stroll in the forest, or playing with your cats or playing a video game, or taking a hot bath, painting your tabletop miniatures, reading a book - many things work and you probably know a few when you think about them.

Some of these things take only an hour or two of your time. Some take a day (going on a hike, sightseeing to a nearby city, visiting a festival...) - but that is all well within the amount of time that you can afford. These mini-holidays can be intensely relaxing. Note that you want to relax your brain, not your body, so they can be sports events - you can come back dead, but relaxed. For me, a weekend of Live Action Roleplaying served that purpose for years. Yes, I came back Sunday evenings, fell into bed and slept for 10 hours. But not thinking about work for two days because you are deeply into something else is exactly what relaxing is about. Lying on the beach isn't relaxing if your thoughts don't manage to make it to the beach as well. Things that force you to focus are best for short bursts of relaxation. Go mountain climbing or skiing or play some team sports - something where the exterior forces you to concentrate and will punish you if your thoughts stray to programming (obviously, safety first!).

These approaches brought me through intense times where I worked way too much, had responsibility for hundreds of people and was at the same time living in two different cities.

Answer 11

Not taking time off is not recommended, you'll then have to accept the risk that this will make things worse, making a very long period of absence necessary. Now, if you are going to ignore the recommended advice and take this risk then the best you can do is bet that the half a billion of years of evolution has optimized your body well enough to pull itself out of this problem.

The few hundred thousand years of evolution that went into the design of your large brain was not long enough to make it run smoothly when working hard for a long time. Here we have to note that it's only since a few centuries that we've started to use our brains in a way that puts it at risk of getting burned out.

You can then use your own body to cure yourself, simply by using your body. Your body is a self-repairing machine, the more you use it, the better it will repair itself. By exercising for longer and more frequently, you will force ancient algorithms for self-repair to kick in at higher gear. You should also change your diet by adding more vegetables and fruits, and increasing the amount of whole grains, brown rice and starches by cutting down on refined fats. Your body has evolved to get its energy from fiber rich foods full of vitamins and minerals, these are absent in the refined oils and fat from which most people get the bulk of their energy from.

If you exercise hard for about an hour a day, you may be able to burn 1000 Kcal more energy per day, allowing you to eat a massive amount of very nutritious foods. The far larger fiber intake will grow your microbiome. It's now known that the microbiome plays a role in brain processes. Most people today only get about 20 grams of fiber a day, the RDA is 40 grams a day. But if you get almost all your calories from unrefined foods, you'll get at least 80 grams of fiber a day. The Hadze people get up to 150 grams of fiber a day:

Hadza consume a huge amount of fiber because throughout the year, they eat fiber-rich tubers and fruit from baobab trees. These staples give them about 100 to 150 grams of fiber each day. That's equivalent to the fiber in 50 bowls of Cheerios — and 10 times more than many Americans eat.

Our brain while imperfect, did evolve under the conditions the Hadza are living, so it may well be that eating 20 grams or less fiber a day makes us far more prone to getting a burnout. Or it could be due to other compounds in our food that are lacking because we eat small amounts of fruits and vegetables. It could be the lack of exercise, or some combination of these factors. You can gamble on all these factors simultaneously by changing your lifestyle.

Not many people in the West eat like like the Hadza do, most people who eat like them are vegans on a whole food plant-based diet. They seem to have plenty of energy at old age, take e.g. Dr Ellsworth Wareham, or Robert Marchand.