Stay active. Exercise is a great way to relieve stress. Your body releases endorphins during exercise, which can help you feel calm. If you exercise 30 - 60 minutes a day, your stress levels can improve. When stressed, take 5 slow, deep breaths with your eyes closed, then roll your shoulders forward 5 times, then back 5 times. This will slow your heart rate and release tension in your neck and shoulders.
Depends. Different people deal with stress differently and therefore need different things to relieve that stress. Often teens find physical activity (running, swimming, basketball) helpful. Meditation, massage or warm baths may help others. Talking to friends, reading a fiction book or even acupuncture may be helpful. Its important for each individual to find what works best for them.