According to the Center for Disease Control, "Regular physical activity in childhood and adolescence improves strength and endurance, helps build healthy bones and muscles, helps control weight, reduces anxiety and stress and increases self-esteem."
The World Helath Organization says "Physical activity has also been associated with psychological benefits in young people by improving their control over symptoms of anxiety and depression. Similarly, participation in physical activity can assist in the social development of young people by providing opportunities for self-expression, building self-confidence, social interaction and integration. It has also been suggested that physically active young people more readily adopt other healthy behaviours (e.g. avoidance of tobacco, alcohol and drug use) and demonstrate higher academic performance at school."