These exercises stretch the muscles and extend the body's various bending points to achieve greater mobility, reduce the risk of muscle strain, and improve balance. Stretching is an important part of warming up before walking, jogging and most other activities, as well as cooling down afterwards. It can also be an excellent activity unto itself – especially for those who need to start out slowly. Yoga and T'ai Chi are activities that focus on flexibility.

Any activity that involves lifting, pulling or pushing against something is a resistance exercise, designed to build muscle strength. Most gym equipment is designed for this purpose, but gardening and many household chores also offer good resistance exercises. So do climbing stairs, calisthenics such as push–ups and sit–ups, and bicycling, rowing and swimming. For other resistance exercises you can do in the water, see the next section.

Water Resistance Exercises
Although swimming laps is an excellent aerobic activity that also works a variety of muscles, it is not the only way to exercise in a pool. The natural resistance of water to your movements affords a wealth of easy muscle developing and aerobic exercises that you can do while wading. And because of the body's natural buoyancy, such exercises put minimal strain on the joints, ligaments, and muscles.

To exercise the arms and shoulders, stand neck–deep with your arms stretched out to both sides. Then bring them together in front of you, keeping them straight as you touch your hands. Bring them back out to the sides and repeat.

Another exercise that works on the legs is the "rocking horse." With the right leg raised and bent at the knee, push off with the left leg and land on the right. Then push back with the right leg, landing on the left. Repeat the exercise for several repetitions.

Of course, never take water for granted. Familiarize yourself with the depth marking before you enter the pool. Even if you're a good swimmer, it's best to have a lifeguard on duty.

Aerobic exercises get your heart and lungs working, while exercising other muscles as well. Jogging is considered a high–impact aerobic exercise because of the stress it places on muscles and joints. Walking and dancing are low–impact exercises, and swimming offers the lowest impact of all. Bicycling is also low–impact, but it can put stress on the muscles and knees.

Aerobic exercise should not raise your heart rate to more than 75% of your heart's maximum capacity. To estimate your maximum heart rate, subtract your age from 220 if you're male, and 226 if you're female. For example, the maximum rate for a 60 year old woman is about 166. Ideally, your aerobic rate should reach a point between 50% and 75% of your maximum heart rate and stay there for 20 minutes or more.

Keep in mind, however, that this is after extensive aerobic training and assumes you're in good cardiovascular health. You should consult your doctor before beginning an aerobic exercise program, and start out slowly.