I used to get stressed about the job and not being able to do everything that was needed, staying back each night, working at home, not stopping to eat, etc. but then one day decided OK that's enough. I do what is needed, do more when its needed, but will not work myself into the ground anymore. The network is running smoothly at the minute, money is OK, people respect me (though same can't be said about the technician here) and I'm happy. I find being respectful to the staff and pupils gets you further than being a loser with them, but being tough when it's needed is also important. The ability to say NO and sticking to your guns is an essential part of any job.
Having a supportive wife and boss who can put up with moody days, and working out my stress in some of the ways others on here have mentioned, (gaming, excerise and so on) means I'm much calmer and don't worry about coming into work anymore.
To Halfmad and others in his situation - if you have a boss who will support you and any changes you need to make to do your job effectively - use them, get them to air your greivances, get them to make others listen. If you haven't got this support I'd look elsewhere for a job, making it clear why you are looking, as it's not likely to get any easier for you and it's not worth near killing yourself for.