Questionnaires on exercise practices, reasons for exercising, factors that would increase exercise, and demographics were mailed to a stratified random sample of 19,510 active duty personnel in all of the United States military services who were stationed at 38 large military installations and a number of remote locations. Responses were returned by 8,572 (55%). Approximately 63% exercised three times a week for 15-20 minutes, and 15% did not exercise at all. Mean BMI was 25.2. The top five reasons for exercising were to improve physical conditioning, have fun, manage weight, improve appearance and manage stress.