We age second after unrelenting second. We won’t notice any difference in our bodies day to day, month to month, even year to year. The clock, however, never stops advancing, destination unknown.

Over time we start to realize our bodies aren’t as spry as that long gone 23-year-old who could exercise all day without the hint of ache or pain.

Chances are, you were or will be about 42 when the revelation really hits.

That’s according to a poll of 2,000 Americans by the market research company OnePoll, which found, on average, people notice the signs of aging around that age. Those first gray hairs or wrinkles can, for some, be quite a shock.

The same group of respondents looked back and estimated when they were at their absolute peak of health. On average, they thought they were 34 when they stood proudly atop fitness mountain.

A significant portion of people — 15% — noticed signs of aging before their 35th year.

One in five admitted they were in denial about growing old. Wrinkles, however, do not go away simply by avoiding the bathroom mirror.

Physicians say, while aging is inevitable, we can take steps no matter how young or ancient we are to expand the time we enjoy good health. Exercise daily, eat a healthy diet and don’t smoke.

If only Spanish conquistador Ponce de Leon had found that fountain of youth 500 years ago. The tale is probably apocryphal. But even if true, Ponce supposedly looked for the fountain in what was then known as La Florida. So, while its waters might have restored youth, it would have been infested with la gators.

And that wouldn’t likely have helped the Spaniards stay youthful. Not for long, anyway.