The world is a sacred vessel, which must not be tampered with or grabbed after. To tamper with it is to spoil it, and to grasp it is to lose it.

Fifteen years ago I ran olympic triathlons nearly every weekend, and I thought that was as good as life could ever get. Back then I was convinced that after forty a gradual decline was inevitable, and probably I’d never be in such good shape again. I was almost thirty-five then — what did I know.

The interruption from all the work travel to last year’s training was frustrating, and I delayed restarting because of the doubts I had about how far I could push myself. Even now, typically when I look in the mirror, it sometimes seems as though I should feel older than I do, especially when I compare the reflection to the memory I have of my younger self. But that kind of thinking ruins life: what is the point of living in the past when the present holds the only meaning?

Last week’s seventy miles is the most I have ever run — and at nearly fifty I can run longer and faster than I ever could in my thirties. There are times when the minor injuries take their toll, both physically and mentally, but now I realize, more than ever, that the only limitations to this aging body are the ones I imagine. The only reason it has taken so long to reach this ability is because I dwelled on what I thought I could not do. It was a classic mistake.

Reaching marathon length this year is just the start. Now that I realize my original fifty mile goal is totally plausible, I also better understand how important the pursuit is: sitting idle and proving my own limitations is more destructive than any damage I could possibly do on the road or in the woods, even if the bears get me.