While I don't have any experience in martial arts, I can definitely concur that physical fitness is a great help when dealing with a stressful work situation. A previous employer had a company subsidized gym on the premises. Even when things got bad, which was most of the time in my last few years there, 30 minutes on the elliptical machine in my target heart rate zone did wonders in improving my disposition.

Right now, I am doing P90X, which includes a yoga program. The 'tip of the day' for that one is to forget about all of the stuff you were doing before, and everything you have to do afterwards. Yoga is definitely worth checking out, whatever your fitness regimen is. The St. Johns mens basketball team started doing yoga when Steve Lavin took over, and has had near-zero injuries since. I can actually touch my toes for the first time I can remember, and colorful language is no longer required to get thru the more challenging poses (Warrior 3, half moon, right angle pose, prayer twists).