Before beginning an aggressive exercise program, you should see your doctor or an exercise professional for screening tests and program advice.

The biggest risk to exercise is not starting. You should consider several factors when choosing an aerobic activity for your personal fitness program. Impact — Some activities involve jumping or pounding that may be uncomfortable or can lead to injury.

Swimming, cross-country skiing, in-line skating, cycling and rowing are easier on the joints.

Convenience — Some aerobic activities require expensive equipment, are seasonal or are not readily available in certain locations.

Tips on Exercising Safely and Soundly