I turned to look

 When I was a teen, running was fun because it felt effortless.

 When in my 20’s it was a way to stay in shape.

 In my 30’s I squeezed it in around kids and my job.

 As I hit my 40’s it was about limits.

 When 50 arrived it was all about laying one more good one down.

 Now in my 60’s it is about letting go and realizing whatever speed or type of forward progress it is is going to be good enough.

 Not sure which era was the best, but running with zero expectations is a learned experience.