I agree with Sarah re: the benefits of self-awareness (when you're trained in it, you get quite good at paying attention to it in yourself!) and of having a collegial network. There's also an art you develop to putting things on a shelf - you have to put your own issues, interests, and values on a shelf each time you sit with a client. Similarly, you learn to leave client sessions on your office shelf so you can go home, have a personal life, and rejuvenate for another day of important service to others. The volume and intensity of the work makes a difference in stress level, for sure, so look for jobs (or create a practice) where you can balance the number of clients and the severity of issues to keep yourself healthy.