“I’m 86 and have walked every day of my life. The public needs to wake up and move.”

“I’m 83 going on 84 years! I find that daily aerobics and walking are fine. But these regimens neglect the rest of the body, and I find the older you get the more attention they need.”

These are two of many comments from readers of my Jan. 12 column on the secrets of successful aging. At the risk of sounding like a broken record, a new series of studies prompts me to again review the myriad benefits to body, mind and longevity of regular physical activity for people of all ages.

Regular exercise is the only well-established fountain of youth, and it’s free. What, I’d like to know, will persuade the majority of Americans who remain sedentary to get off their duffs and give their bodies the workout they deserve? My hope is that every new testimonial to the value of exercise will win a few more converts until everyone is doing it.

In a commentary on the new studies, published Jan. 25 in The Archives of Internal Medicine, two geriatricians, Dr. Marco Pahor of the University of Florida and Dr. Jeff Williamson of Winston-Salem, N.C., pointed to “the power of higher levels of physical activity to aid in the prevention of late-life disability owing to either cognitive impairment or physical impairment, separately or together.”