The bones of your spine are separated by pads called discs. As you age, these discs dry out and become smaller. However, regular exercise compresses and relaxes these discs as you move up and down. This helps to keep the discs from shrinking and maintains your height. Regular exercise also helps to strengthen bones and keep them from bending or being crushed. One study from Israel showed that people who exercise regularly lose only half as much height as people who never exercise -- just 2.6 centimeters compared with 5.5 centimeters. If you have not already started exercising to prevent heart attacks, diabetes, high blood pressure, high cholesterol and loss of mental function, and just to keep you feeling good, you should exercise to help you stand taller as you age.

When it comes to preventing osteoporosis, it matters little what you did when you were young, it's what you do now that counts. A study from Malmo University in Sweden shows that men who were highly competitive soccer players in their youth and then gave up active sports did not have bigger and stronger bones and did not have fewer bone fractures than people who never exercised at all. On the other hand, people who did not exercise in their youth, but started and continued their exercise programs into later life did have larger and stronger bones.

In spite of this study, you still should start exercising when you are young. Good habits are usually developed when you are young. People who start exercising at an early age usually benefit by learning how to exercise. They take a harder workout on one day, followed by easy workouts until their muscle soreness disappears and they learn to take off when their muscles are sore.

Dr. Gabe Mirkin has been a radio talk show host for 25 years and practicing physician for more than 40 years; he is board certified in four specialties, including sports medicine. Read or listen to hundreds of his fitness and health reports at http://www.DrMirkin.com