When I started getting plantar fasciitis, everyone I talked to told me it was because of the loose sand on the beach and how I didn’t take days off and lack of shoes and no arch support and no heel support and running on a side-slope all the time. Then I read that runners get this all the time everywhere, so maybe it didn’t have anything to do with how I was doing everything wrong.

This condition, as everyone addicted to endorphins knows, is when your body is warning you through burning pain to stop doing something. No one entertains the idea that your body is a stupid liar that cannot be trusted and is just trying to trick you into kicking back and watching more TV.

There may also be a thing about age, though, and not really age, but having hard miles under your belt – a whole lot of hard miles. There’s a huge number of guys in their 20s with plenty of miles. They usually came out of organized sports, picked up some individual sports, and just kept sports as part of their routine.

But the 30s, a significant swath of that group stops going after the miles. In return, as a bonus awarded by snack-chip companies, their increasing buoyancy makes them practically drown proof.

In your 40s, wherever you live, you start to get to know the names and faces of each and every human in your age class that’s still pushing out miles of some kind. We fight back against age, fat, a resting heart rate that is not resting, blood pressure, flab, the whole kaboodle of decline.

After the 40s, you’ve got to be sick in the head to keep hammering on your joints like we do. There’s really no explanation for it. And it’s not just the miles, it’s those hard miles.

You get where you can tell in a glance if someone in their 50s, 60s and 70s takes care of themselves. The worn skin, scars, the layers of muscle built like sedimentary rock. The way they walk, and maybe hobble a bit. The way they go up stairs, or throw around a mower, or drop on their back to scoot under a car.

It’s an unspoken, unrecognized demographic. Survivors of hard miles. Of injuries and incidents and close calls and bad choices. Of being stranded in bad weather at the worst time. Of grinding it out so often that your legs start to push even before you brain consciously thinks that you need to start to push.

That marathon – the one that beat me down like a wet dog – running it came down to two simple decisions. First, would I have to pay to enter? I’m not that kind of grinder, not a bit.

The second decision was about running that far. I’d never run over about six miles without stopping before, and that was high school. In a rugby game we’d run farther, but there were a lot of breaks for scrums and lineouts and fights and beer. I’ve only run one 5k, when I was like 12. I’m not a joiner. I don’t need logo t-shirts or commemorative medals.

I wonder if running, for some, is always a way to build toward an event. Just something they have to do so they can get a t-shirt or medal. We used to bike with guys and girls like that in Colorado, the ones who were always in the local town MTB race series. They were no fun to ride with because every ride was training for them.

They wouldn’t stop and try to haul home a free fish. Or talk to a lost tourist. Or take a picture of a group of them so that one would not have to be the selfie-taking-geek.

It’d be interesting to do a study on those who grind out hard miles in a sport all their lives, but don’t do it for any competitive reason. And another study for the competitors, so that of course they could be graded and ranked in yet another way.

But I don’t think the study is possible. The ones who are out there on their own have no need to have their addiction explained to them. It just is what it is. They live with it in their own way.