The older I've gotten, the more aware I am about how stress, etc. affects me.  I've been at my current position for over 11 years and it's the kinds of projects I get to do that prevent me from getting burned out and bored.  Additionally, I typically enjoy a 40 hour work week--that's one thing that's always been a factor for me when accepting a position--I'd rather take lower pay and work 40 hours/week versus a higher pay and not have a life.  Technically I'm on call 24/7/365 but as team lead of a now competent group of developers, I've worked to get them up to speed and needed training to be able to handle things without calling me on my vacations, etc.

That's not to say it's been an easy time or that I still don't have issues with burn out but nowadays, it's due to some people and their lack of organization and planning.  I've gotten better about recognizing when I'm getting to that point, taking some time off to clear my head and get away from it, etc.  And I've made it clear, especially to a contractor we have that used to be the boss--my personal time is MY personal time and when I say that I'm busy on a Saturday and that lack of planning on your part doesn't make it a crisis on mine.

Sometimes the best thing for productivity is to stand up for yourself and take time for yourself.  It took me a long time to realize that but I'm glad I did and I'm fortunate enough to now have a boss that recognizes the need for that as well.