Stress is a normal reaction to life for people of all ages.
It's caused by your body's instinct to protect itself from emotional or physical pressure or, in extreme situations, from danger. With all the things that you're doing and all the things that are out of your control because of your age, it's easy to feel overwhelmed. Things that you can't control are often the most frustrating. Maybe your parents are fighting, or your social life is a mess. A common reaction to stress is to criticize yourself.