Great question. A condition that seems to plague MANY project managers including myself... at least until I had my heart attack.
Two parts, in my experience.
1) Find balance with outside interests. Project management sucks you in, and becomes lifestyle, well beyond just a "job" that you can close the door on at 5:00. They key is to ensure you have a balance of outside interests so you don't place so much of your sense of worth on your performance as a project manager. Play soccer, play chess, find a wife or reinvest in the one you have, go for walks, run 10ks, play ultimate frisbee, restore a car, learn dance, get on a bowling league, get involved in a community service role that pulls at your heart strings. Pretty much anything that will diversify your self-identity. By doing so, you will also come across MUCH more rational with your team and broader stakeholder group.
2) Take power breaks. And don't confuse these with vacations. I live in the Pacific Northwest and have taken 3-day weekends in Cabo San Lucas. I park myself on the sand, and sleep a ton, read novels, drink beer, sleep more, eat more, and just relax. Flights are direct and inexpensive, and AlaskaAir has killer 3-day packages with hotels. Anywhere that forces you to disconnect can work. You know it's not going to change anything when you get back, but the time to just unplug, sleep, commune with nature or other cultures is a powerful sedative. And you come back with renewed vitality.
I suppose I should slip a 3rd suggestion in as well. Spend your overtime teaching others to do the work they're not doing, and don't make up for what they don't do. Have a clear vision of what needs to be done, be engaging with your directs and be clear and unambiguous with them what you expect of them, and hold them accountable; Penalty consequences for pattern of failures, and affirming consequences for pattern of success.
That last tip is probably the most enduring I can offer, but the hardest to get your arms around, because it typically goes to your personality type. And changes at that level can be very hard indeed.
Hope this helps...