Young people need to move. Because our thrifty physiologies evolved to build capacity in response to demand, sufficient physical activity during the first decades of life is indispensable for developing a healthy body. At least an hour a day of moderate to vigorous physical activity reduces children’s risk of obesity and helps them grow healthy muscles, bones, hearts, blood vessels, digestive systems, and even brains. Children who get more physical activity learn more and are smarter, happier, and less prone to depression and other mood disorders.
