New Delhi, May 16 -- Throughout history, few things have inspired as much quackery as the pills, potions and promises to slow ageing, boost vitality, or extend life. Yet, amid the hype and hollow claims, a few golden truths remain. As far back as 400 BC, Hippocrates, widely considered the father of modern medicine, famously said, "Walking is man's best medicine." More than two millennia later, science is finally catching up with that wisdom.

People who walk more than 8,000 steps a day reduce their risk of premature death by half, compared to those who walk fewer than 5,000 steps - the threshold for a sedentary lifestyle. But beyond 8,000 steps, the benefits tend to plateau, which challenges the long-held belief in the magic of 10,000 st...