Heart disease is almost twice as likely to develop in inactive people. Being physically inactive is a risk factor for heart disease (along with cigarette smoking, high blood pressure, high blood cholesterol, and being overweight). The more risk factors you have, the greater your chance of developing heart disease. Regular physical activity can reduce this risk.

Most Americans are very busy, but not very active. Every American adult should strive to get at least 30 minutes of moderate-intensity physical activity daily. If you are inactive now, begin by doing a few minutes of exercise each day. Gradually increase the time you exercise and the intensity of the activity.

Low- to moderate-intensity activities, such as walking, stair climbing, yardwork, moderate to heavy housework, and dancing, can have both short- and long-term benefits. If you are inactive, the key is to get started. One great way is to take a walk for 10 to 15 minutes during your lunch break, or take your dog for a walk every day. Your goal should be to increase the duration of exercise to at least 30 minutes every day at a moderate intensity level.

It takes only a few minutes a day to become more physically active. If you don't have 30 minutes in your schedule for an exercise break, try to find two 15-minute periods or even three 10-minute periods. Once you discover how much you enjoy these exercise breaks, they may become a habit you can't live without.

People who engage in regular physical activity experience health benefits even if they don't lose weight. Regular physical activity can make you more energetic, reduce stress, and help you relax. Physical activity helps to tone and strengthen your muscles. People who exercise regularly have a lower risk of developing heart disease, diabetes, and some types of cancer.

Less intense physical activities — if performed daily — can have some long-term health benefits, such as decreasing your risk of heart disease. But in order to improve your fitness level, you need regular, brisk, and sustained exercise for at least 30 minutes, three to four times a week. This type of exercise includes brisk walking, jogging, or swimming. Moderate- to higher-intensity aerobic exercise burns more calories per minute of activity than low-intensity workouts. To increase muscle strength, add two to three sessions of resistance training each week. Stretch after your workouts to maintain flexibility.

Although we tend to become less active with age, physical activity is extremely important at all ages. In fact, older people who exercise regularly increase their capacity to do everyday activities. In general, middle-aged and older people benefit from regular physical activity just as much as young people do. What is important, no matter what your age, is tailoring your activity program to your fitness level.

Many activities require little or no equipment. For example, brisk walking only requires a comfortable pair of walking shoes. Also, many communities offer free or inexpensive recreational facilities and exercise classes. Shopping malls are excellent places to walk, especially for people who do not wish to walk alone, in the dark, or in bad weather.

The most common risk of exercising is injury to the muscles and joints. Such injuries are usually caused by exercising too hard for too long, particularly if a person has been inactive for some time. To avoid injuries, try to build up your level of activity gradually. Slowly stretch after you finish exercising while your body and muscles are still warm.

You should ask your doctor before you start (or greatly increase) your physical activity if you are being treated for a medical condition or are at higher risk of heart disease because of high blood pressure, high cholesterol, or smoking. Also, don't start without your doctor's permission if you have pains or pressure in your chest and shoulder area, tend to feel dizzy or faint, get very breathless after mild exertion, are middle-age or older and have not been physically active, or plan a fairly vigorous activity program. If none of these applies, start slow and get moving.

People who include regular physical activity in their lives after a heart attack improve their chances of survival and can improve how they feel and look. Regular physical activity can also help to reduce the risk of having another heart attack. If you have had a heart attack, consult your doctor to be sure you are following a safe and effective exercise program.

Varying your routine allows you to work different muscle groups. For example, do brisk walking on Monday, Thursday, and Friday. Do resistance training with weights on Wednesday and Saturday. And swim or ride a bike on Tuesday and Sunday. Doing different types of exercise also keeps you from getting bored. To make exercising even more fun, you can ask a friend or family member to exercise with you.