For many people, starting an exercise program for the first time is quite safe. But depending on your age and whether you have certain cardiovascular risk factors, you may need to see your doctor before starting a program of vigorous (as opposed to moderate) aerobic activity. The American Council on Exercise offers the following advice to help you determine if you need a doctor's okay before starting an exercise program.

If you are planning to participate in vigorous activities and are a man over 45 or a woman over 55, you should have a medical exam first. The same is true if you have two or more coronary artery disease risk factors, which include: