For me, life is peaceful for most of time.But everyone has his or her bad day.For lots of teens, the bad things may mean too much homework, terrible achievement, relationship between people around them is in a mess and so on. In my experience, they will be hurt just because of a simple word. They are too weak to face their lives. And it's really easy for them to feel lonely away from the world. It's hard to say that all wrong they should assume, or all of these things are caused by their parents, teacher,school. In my opinion, teens like to magnify commonplace things,and vent to their pressure. This pressure is from different sides.
Some are from their parents' and teachers' requirements. Some are alone with these physical changes. These body changes may make them feel more confused. They may want to know what the maximum limit of them, so they express their strong feelings. During those things, they may felt pains.
Teens feel pains in the road to become adults. Because of that, they could grow up. Maybe that's the meaning of growing pains.