Extensive research in humans and animals has established that exercise has beneficial effects on general health as well as on the health and functioning of the brain. For example, the benefits of exercise on cardiovascular health, obesity, diabetes, and cancer progression have been well described. Moreover, recent research has elucidated aspects of cognitive health and function that are improved by exercise, as well as mechanisms that might be mediating these cognitive benefits. In humans, the greatest benefits of exercise on cognitive function have been demonstrated in aged populations, in part because much human research focuses on interventions to counteract the normal cognitive decline that is associated with aging. The breadth of human exercise studies has expanded in recent years, revealing that beneficial effects of exercise on the brain extend across the life span, from the aged to young adults, adolescents, and children, and even to prenatal development.