I am 72. That is not old these days. I am sure there are Hiroshima-bomb-year-baby peers out there running marathons. Poor bastards. But it is old enough to set up a few informative signs along the path downhill. I remember the Burma Shave signs.
Sign #1: No one is watching. No one really gives a shit what you do, so relax. It does not matter what you wear, as long as you are decent and not flamboyantly overdressed. No one is going to look at you anyway. You are functionally invisible. That no one, by the way, includes any deities. By now you have outlived that fairytale.
Sign #2: Time is tricky. Sure, in science it helps to pretend we have corralled time with numbers into some sort of lockstep, but you know better. The real clock is chaos. Time is not solid; it is liquid and vapor, an aurora borealis. Ask a hawk what time it is. There are languages that have no word for time. Five years ago? Five days ago? Not yet? What is the difference? Hard to grasp? Wait, you will find out. Time thins and pales and vanishes like hair.
Sign #3: Perfection is an illusion. Life is a mess; that is why it works. Evolution is always correcting itself (or fucking up again). Learn to savor the faults in things. As the poet Charles Olson learned: “The only thing that does not change / is the will to change.”
Sign #4: Your inner voice is your best friend. There may have been a time when it gave you bum advice, back when hormones had a say; but now it is one hundred percent on your side. It only wants to help. After all, where would it be without you? My inner voice has become a sort of son, cautioning the old-man brain inside my head. “One thing at a time, gramps.” “You left it in the other room.” “Watch the step.” We have our laughs.
Sign #5: Go slow. No rush—all your potential is behind you.
There are a couple more, but I forgot them.