You’ve seen and admired them—the men and women who seem to drink regularly from the fountain of youth. Although their hair may gray, they never seem any older. Rather, they age gracefully without acquiring a disabling disease, losing precious memory, gaining excess weight or losing their agility.

Fortunately for us, the key to aging successfully is simple and accessible. The most effective defense against the inevitable onslaught of aging is exercise.

Exercise Changes the Length and Quality of Cells

Although most of us knew that regular exercise was good for us, we are just now beginning to understanding its positive impact at the cellular level. In an article in the "Archives of Internal Medicine," Vol. 168, No.2, January 28, 2008, “The Association between Physical Activity in Leisure Time and Leukocyte Telomere Length,” researchers were able to measure the beneficial effect of exercise on cells.

The study was based on the observation that telomeres in white blood cells erode and shorten during the aging process. Consequently, their length and quality are biological indicators of human aging. Researchers hypothesized that comparing the length and quality of the telomeres in exercising and sedentary twins would indicate whether exercise had an impact on the rate of cellular aging.

In the London-based study of 1,200 sets of twins, researchers found that the longer, healthier telomeres of the active twin indicated a younger biological age—sometimes by as much as nine years—when compared with the biological age indicated by the shorter, degraded telomeres of the sedentary twin.

Our brains may benefit from exercise as well. Dr. Waneen Spirduso, author of "Exercise and Its Mediating Effects on Cognition," argues that exercise improves mental functions such as recall, learning and abstract reasoning. Exercise may even help prevent or delay the onset of Alzheimer’s and dementia.

Exercise Can Take Seven to Ten Years Off the Age of Your Brain

No one is more enthusiastic about the neurological benefits of exercise than Harvard University professor and psychiatrist John Ratey, author of "Spark: The Revolutionary New Science of Exercise and the Brain." In “Exercise Is Good for the Brain,” an article in the "Los Angeles Times" (March 17, 2008), Dr. Ratey claims that aerobic exercise can delay cognitive decline by as much as seven to ten years. [CMS]

Further, because exercise creates neuron growth, Dr. Ratey calls exercise “Miracle-Gro for the brain.” He believes that exercise is the single best tool we have for keeping our brain functioning at its highest level. Dr. Ratey also encourages us to exercise with friends so we experience the social benefit as well.

How ironic if the elusive fountain of youth turned out instead to be a foundation for youth, one built simply on regular, consistent exercise. Indeed, the evidence is so compelling that I’m turning off the computer and heading outside for a walk.