Physical activity can aid in the prevention of cardiovascular disease, diabetes, and obesity. Even moderately intense physical activity such as brisk walking is beneficial when done regularly for a total of 30 minutes or longer. Besides exercise can be fun. The summer is a great time to swim, jog, play tennis, or bike. Pressed for time? Try jumping rope for 20 minutes, walking during your lunch breaks, or running in place while enjoying your favorite television program.