1. Prepare for time out if the stressful situation is drawn-out. If it's tax season and you're a tax accountant, build in regular breaks during each day and take a day off once in a while when you are away from your cell phone, computer, email, etc. Use the breaks to refresh your mind and body and recharge. Power nap, take a brisk walk, go fishing, run, fly a kite, watch a favorite movie, read a poem!
2. If it's a stressful meeting with someone, agree upfront to work for a period of time, then take a break, and then work again, and then take a break. During the breaks, make sure you do something to relieve whatever stress has built up in your body. Do 6 slow, deep cleansing breaths. Drink a tall glass of water in slow, measured sips and really taste the water, erasing all other thoughts and worries from your mind. Then you can re-enter the meeting in a calmer frame of mind.