You're too old to be having melt-downs and it's a bad example to set for your relatively new child. I think there are a couple clues in the description you've added above though. Sitting in a chair for hours is necessary as a software developer but that shouldn't mean sitting in one position. If you can't stand for part of your workday, at least change the position you're sitting in. The terms "shitty job" and "dead-in-the-water career" are a more pressing matter - your attitude is going to be pretty well correlated to your feelings about your job. If you can't simply change jobs, try to find a way to "make it new". One of my tricks is to "see it with new eyes" which can be practiced by driving through your town and imagining it's your first time there (I've seen things doing this that I'd simply never noticed before.) Another thing you can do is find ways to do your job that result in you learning new skills. Finally, when you're not working you should get away from your desk. Doing housework can be cathartic and getting some exercise will definitely help.