You are breathing since you have born but the proper breathing i.e. deep breathing will calm your mind and will distress you. Also, it is a temporary alternative to destress!
Go to 8tracks and search for "calm" you will get so many song playlists. Just play them and listen! Or if you have any of your favorite songs then listen to them.
Go and get a little walk outside. See the people, trees and if you are some of those blessed peoples who lives in villages then you may see sparrows & butterflies. Outside world is so awesome.
Visit any of your friends and talk with him or go and play any game or go to movies or a restaurant or to meet another friend. Talking with friends and spending times with them really heals you and helps to destress.
Take a nap
Go to sleep. Sleep and forget every trouble you have just sleep. Sometimes taking a nap for 10 minutes helps you to remove all your tensions and to get a fresh mind.