Physical activity expends energy, which balances energy consumed and maintains normal weight. Increased physical activity is associated with lower risks for chronic diseases; cardiovascular diseases, such as coronary heart disease and hypertension and other conditions, such as colon cancer and diabetes.[41] Increased levels of physical activity are recommended, as this has been associated with lower risk for premature death. For children and adolescents, regular physical activity not only helps to control weight but also improves strength and endurance, builds healthy bones and muscles, reduces stress, and increases self-esteem.[41] However, levels of physical activity in childhood have declined in recent years, concomitant with the increased focus on academic achievement in schools and the increased use of electronic media and Internet at home.