You have already identified the need to achieve some level of balance in you life, which is an essential first step in the process.
I found that being a workaholic was creating significant issues for my relationships and health as I moved through my thirties; what is sustainable when you are at the start of your career with little or no consequence becomes more challenging.
Workaholics can easily get trapped in a "stress cycle" - not working causes them "stress spikes", which when addressed by working builds up the background stress. Their stress levels impact on their communication and productivity, which leads to a new crisis, and another "stress spike."
Based on what I went through to resolve this issue I would suggest:
Develop an understanding of why you work like this.
You are driven to work hard in order to satisfy some psychological need that you have; its not a bad thing, but you need to understand it more to be able to control it. I found the PCM (Process Commuication Model) ugely helpful in understanding my own "workaholic" nature, what the negative impacts could be and how to manage it. Other instruments like MBTI can also be helpful to understand what drives you, as well as the kinds of things that can help you relax and address the same need.
Go Cold Turkey
Thinking of your work habits as an addiction is useful, as it makes you realise that change will be difficult. In my case, I created a work-home separation first of all - with a 100% cut-off between work and home activities. This can be hard in a mobile age - seperate phones, decoupling e-mail addresses and keeping "work" and "life" social media seperate is not always easy, but without doing this you will be sucked back into the "work vortex", especially at first.
Fill The Gap
If work has been filling up your life, then when it stops, you'll have a big gap to be filled. One of the things I was advised to do to reduce stress was to schedule 20 minutes a day of time to be wasted doing something fun, which helped. I also ended up putting on weight, because in the evenings I would get restless, and eat snacks instead of working. So - you will need to find something constructive to do instead of work.
Something that involves physical activity is great as this is the only way of really dealing with stress, and going "cold turkey" is stressful!
Things like scheduled classes or clubs (gym, dance, martial arts, tennis, bowling, group cycle, sailing) set for an hour or so after work officially ends can be very effective, especially with friends. A regular commitment where you let people down if you don't go can be a good motivator.
However - you can't do this all the time, so you need a few other things. I ended up making a list of the things I used to like doing, and the things I wanted to learn and never did.
This lead me to some interesting evening classes, and to take up the guitar, tennis, running, swimming and salsa dancing. I also read again, like I used to.
When you are better...
I have been "clean" of my workaholic nature for about five years; my career and workplace satisfaction have sky rocketed and frankly, I'm a much better person to know. I do let work into "my" time occasionaly now, but it has to be when it is critical to the team in a strategic sense, not a tactical win. I always ensure I "timebox" the work, and don't intermingle the work activity with other "home" actvities, to maintain the separation.