I also read this and thought of IT/software I left one job after being completely burnt out working around the clock and was replaced by FOUR people. That made me pretty mad. I also find this playing out when I do volunteer work - I keep stepping in when other people are not doing their job, and I just wind up resenting everyone and quitting.

I have been steadily improving my boundaries. Stop working so many hours. Sign up for a class that makes you unavailable (or some other activity). But really, when it comes down to it, just start saying no to all this extra work. The job you are in right now might be okay if you aren't working yourself to death and don't feel taken advantage of.