When I was a kid, the computer was my favorite toy. I would spend hours of time coding just for the fun of it. This love of computers led to a career in software development, which has been greatly rewarding! But, once anything becomes a job it is difficult to stay in love with it -- even when your job is open source.
So, find a hobby? Do something else! That's great, but for me nothing has the same mental reward as a good computer project. It just sucks to constantly be at the mercy of other people's demands...
My solution has been simple: retro-computing! I don't just use the computers of my youth, I make them do interesting new things! It's crazy, of course...but I love it! Maybe hearing about my experiences could be useful for you to find your way to avoid burnout? You may not want to dig-out an 8-bit micro for your next project, but maybe a robot, or an arduino, or...