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My boss wants to send me to a costly external training (all cost covered by the company). I like the topic, and I believe this training could be interesting and beneficial. Unfortunately however I generally do not really feel myself happy at the company. I get tasks that I am able to solve only with enormous struggle, and sometimes I am not able to solve them at all. So I decided to wait for my next project, if it turns out to be as hard as the most recent ones, I will quit. The training in question might be beneficial, might improve some aspects, but with a project as complex as ours definitely can't solve everything. If I take the training and a month later I quit the job, I feel myself bad (and unfair). On the other hand I might get just lucky, maybe this next project is not as hard as the most recent ones (earlier I had some pleasant ones) so I can stay and work within my comfort zone, and then the training might come handy... So my question is how to explain this situation to my boss.