A friend of mine posted to her Facebook page recently criticizing a whole category of ageist comments along the lines of “You’re only as old as you feel.”

It caught my interest in particular because I’d been mentally composing a post about how I just turned 58, but I’m not suffering the aches and pains that supposedly go along with getting old. My friend’s post reminded me that referring to this as “feeling young” is problematic. And yet, I find that I come down on the other side of this issue. Sure, there is a certain irrefutable accuracy to say that your age is the current year minus your birth year, but age is many things besides a mathematical calculation—at a minimum it’s a social construction, and also perhaps a collection of biological circumstances.

It’s true that what I mean—and what perhaps I should say—is I feel good. Better, in fact, than I’ve felt in years. I’m stronger, more flexible, and more agile than I’ve been in longer than I can remember. I move with more ease, more power, and more control. I have more endurance. I’m certainly more comfortable in my own skin.

A lot of this is just good luck, of course—good genes, avoiding serious injuries and serious illnesses so far.

Beyond good luck I credit my movement practice for most of the rest. Taiji. Walking and hiking. Running (merely an adjunct, but one I enjoy in particular). After years of lifting with machines to little noticeable effect I now do almost all my strength training with bodyweight exercises and am having much more success. (The main exception to pure bodyweight exercise is doing kettlebell swings for my high-intensity interval training, which I ought to write about because it seems to be doing some good, and is also quick and fun.) Push hands I wrote about recently. Animal movement ditto. So new I haven’t had a chance to write much about it yet, I did yoga for the first time last week.

But to bring this back full circle, I’m not so sure that it’s wrong to talk about “feeling young.” My friend is right—growing old is a privilege not everyone enjoys. It is indeed better than the alternative: dying young. But just as I can see her objections to denying age (as if refusing to acknowledge it meant something), I object to denying one’s felt experience. If someone says that they “feel young,” does an appeal to mere arithmetic justify correcting them?

Certainly I am not the only person to feel this way. There are always people trying to express health and fitness in terms of age. There are websites that will suggest a guess as to your physiological age vaguely based on your weight and your activity level. Various practitioners of various disciplines will measure specific things ranging from your maximum heart rate to the length of your telomeres and use the results to calculate a biological age.

They’re all pretty dubious, but I find that I do not object in principle to thinking and talking about concepts like health, fitness, and vitality in terms of age. Even though there are many unhealthy young people and many old people who are fit and vital, I think the notion resonates in a useful way.

As for me, I feel good. I also feel younger than I’ve felt in years.