I like to go out back and take a nice swim and then float around with a cold beer. Relaxes me right out. If I have to stay inside, the it's good PC game. Both work to keep my stress level down.
I read to get my mind off things, I also clean and cook to relieve stress.
I sit and eat the heads off of Peeps. I feel great after that.
Read a book take a nap
Go jogging, meditation, yoga, calisthenics, or just jump into a cold shower.
Normal daily routine for me, therefore stress is non-existing.
Go to the beach. Just sitting there and smelling the salt air, watching the waves and feeling the sea breeze can remove a month's worth of stress in 15 minutes. If it doesn't work, heading to the bar and having a beer while watching the waves ain't bad either.