A couple of years ago, I decided that I was going to try to run a half-marathon. I thought it would be a good test of my physical fitness, my determination, my perseverance and my utter cluelessness. It didn’t matter how old I was, I thought; I could be just as stupid as I used to be.

I never did run that half-marathon. I would like now to explain why.

First, I found out that a full marathon is indeed 26.2 miles long, or 26.1 miles longer than walking to the mailbox to get the mail. Second, I found out that a half-marathon is, in fact, half a marathon.

To get a better grasp of what that means: technically speaking, it’s 13.1 miles, 21.08 kilometers or, in England, 16.7 imperial liters. It’s a lot of liters. It is, in fact, the equivalent of running to the supermarket, then running back home, then finding out you didn’t buy anything at the supermarket and having to run all the way back, just for a loaf of bread.

And then it turns out the supermarket is closed. And that’s assuming that the bread was any good and the supermarket was only one state away, and mostly downhill.

In addition, I discovered, you can’t just run a half-marathon without preparation apparently. You need to train for it. I would have much preferred that meant I needed to book on Amtrak. But it turns out that means doing a lot of running even before you have to do a lot of running.

Yes, I know it seems unfair.

In particular, in training for a long race, you are supposed to start small and build up over time. I was fine with starting small. I was so fine with it, I stayed small.

You are supposed to slowly increase your mileage until running a half-marathon is as easy as going to the supermarket and buying a loaf of bread. We know how that turned out.

When I was training, after running about three or four miles I would begin to get that certain feeling you get, that runner’s high — you know, that moment when you are certain you are surely going to die.

My feet would swell, my legs would hurt, my back would ache and my breathing would be labored. It was sort of like when I’m watching a presidential press conference.

In addition, all that preparation to run a half-marathon takes a lot of time, and, frankly, I’m a very busy person. I have naps to take, emails from acquaintances to ignore, dishes in the sink not to wash. Sometimes, I have to spend whole days figuring out how many characters I have left when I want to tweet something.

But perhaps the most important reason I gave up on my half-marathon quest was that I found out I could just buy one of those “13.1” bumper stickers and not have to prove that I earned it.