Relaxing:
If I find myself stressing out during the day, I'll take several slow belly breaths, expanding as deep into the diaphragm as I can. That usually does the trick immediately.
When I come home from work after a particularly stressful day and I'm still feeling tensed up, a good long walk always helps, but I have to watch that it doesn't turn into an angry, stomping kind of walk. I try to practice Mindfull meditation and dispassionately move my body and observe my surroundings and allow my thoughts to come and go like clouds.
On one of my office PCs, I have a screen saver that is like a psychedelic light show with shapes and colors and patterns that are incredibly hypnotic. I sometimes take a break to just stare at it for about five or ten minutes or an hour or two, depending on how long before someone comes into my office and breaks me out of my trance.
