Not Just IT
I started out as a city planner and go into IT because I needed tools for policy analysis etc. I'm here to say, this isn't just about IT jobs.
I came to the realization that I could work literally 24/7 and not get done all the stuff that city management expected me to do. I also realized that 2 hours after I croaked, they'd have emptied my cube and dumped the unfinished work on someone else's head. Fortunately, I also came to the realization that the world wouldn't end if most of what they wanted never got done at all.
So, I decided to put in what I thought was reasonable hours at whatever job I took, on the most urgent/important stuff, and to produce output that I considered workmanlike or better. I wound up having a good bit of fun, getting a lot done, and feeling pretty good about myself. Oh, and I personally decided that 50-60 hr weeks were OK, and that the occasional all-nighter or all-weekend push were just part of the job. And, especially as I've gotten older, I've come to realize that excessive overtime is unproductive if not counterproductive.
In the interim I've also managed to have a happy family life, and put myself thru a master's and almost to a PhD in my spare time.
