I turned 40 this year, and as cliche as it sounds, the switch suddenly flipped in my head. Oh crap, I’m not young anymore.

I was out walking the dog at dusk and saw a high school kid just running down the street. He was moving fast, not breathing hard, like he had nowhere to go in a hurry and was just clicking off the miles. I did a double take. Maybe it was the feeling of the moment that matched a long ago memory, but in that moment I had an out of body experience, like looking at a version of me, maybe 25 years ago. A version of me that would just take off on a run at dusk, basking in the coolness of the evening and the invincibility of the feeling of moving fast. And I felt envious - maybe of his potential - of places to go, people yet to meet, achievements to have reached.

This year I started internalizing the idea that I’m old. Well, maybe not old per se, but that I’m not young anymore. I strained a quad recently on a tough workout - I’ve never gotten that kind of injury. I’m not recovering as fast anymore from difficult workouts. It’s not as easy to power through the day on my normal six hours of sleep. My daughter said to me recently: Daddy you’re always tired. The girl’s right.

Thoughts intrude: Have I accomplished enough? Am I past my prime? Will I still be able to achieve my goals in running performance, career accomplishments, financial security? When I look around me, I feel uneasy, like everyone has done more, or that I am being left behind (ahem, AI). Or I feel uncomfortable, like I might lose it all with one unfortunate life circumstance. Or I look at my life today and think - I don’t have room to squeeze in another thing, but there are so many things I want to do.

Then I catch myself and think that it’s funny that if my 20 year old self saw where I am now, he would be straight up amazed. That his 20-year future self truly did have everything he needed, with the people and family around him that he could only dream about. He would also be strangely comforted to know that his accomplishments are fleeting, and the truly Good things in life were always in reach.