definition of physical activity: Moving the body to promote health and wellness. Physical activity may strengthen muscles, strengthen the cardiovascular system, improve athletic skills, help with weight loss and weight control, and improve the mind. Physical activity has been found to increase levels of beta endorphins, which may create the feeling of a "runner's high." Physical activity also is done for pure enjoyment. It can include running, gymnastics, dance, horseback riding, soccer, hiking, surfing, yoga, and more. Physical activity is often overlooked in the lives of children, especially children with special needs.