You may have heard that "you're as young as you feel." But, if the thought of aging causes you to shudder, perhaps you're just going about it wrong. Experts believe that our sedentary lifestyles and high-fat diets help create unnecessary ill health and diminished mental, physical and emotional capabilities as we age. 

  Roger Landry, M.D., M.P.H., retired chief of aerospace, occupational and preventive medicine for the Air Force, believes people can stay healthy and productive long into their 80s, 90s or beyond.

  Landry, who is conducting a study on the effects of lifestyle on aging, warns that already high health-care spending, which currently accounts for 17 percent of the gross national product, could spin out of control during the final stages of life. "As baby boomers age, health care costs will become unmanageable," he says, adding that the most important thing people can do to improve their health and reduce health-care costs at all ages is to exercise.

  The incidence of type 2 diabetes, heart disease and other life-threatening illnesses, due in part to obesity, are occurring more often and to younger people.* Although medical technology has lengthened life expectancy, without adopting lifestyle changes people may be sick during much of their old age, says Landry. 

  Ill health and diminished function in the elderly may not be inevitable. Jay Olansky, senior scientist at the Center on Aging at the University of Chicago, thinks exercise is the closest thing we have to the fountain of youth and that inactivity, more than age, is the greatest enemy of health and fitness. 

  Aging well, according to results from a recent MacArthur Foundation study on aging, may merely be a matter of three things: physical and mental fitness, strong social connections and identifying and avoiding risk factors.

  A simple anti-aging plan set forth by Johns Hopkins Medicine suggests you:

• Exercise. An effective routine includes regular endurance training (walking, biking etc.) and strength training. 
• Eat a healthful diet. Eat plenty of fruits and vegetables, low-fat dairy and whole grains.
• Cultivate satisfying relationships. Social connections help preserve physical and cognitive function by lowering levels of stress hormones in the blood.
• Drink enough water. Your body needs six to eight glasses of water daily to function properly.
• Challenge your mind. Take classes and learn new skills to engage the three key factors that predict strong mental function: regular physical activity, social support and belief in your ability.
• Reduce stress. Consider stress-reducing techniques such as meditation, yoga or exercise.
• Limit alcohol consumption and don't smoke.

  Although experts suggest developing and maintaining healthful habits in youth, it's never too late. 

  The necessary changes are not huge or costly, says Landry. "For instance, if sedentary people just walk for 30 minutes daily three or four days a week, they will see benefits quickly," he says.

  Evidence shows that quality and quantity of life may be in your hands.