I often look at children playing on swings, monkey bars, climbing bars and the like - having so much fun - and I wonder - "When and why did I stop?" and even wondering if I could start again. And, it seems to me that the vast plurality of children engage in such play to some degree or another.

So, why does it stop? When?

I have a friend down the street who will ride a bike only if I ask him to accompany me. He is a couple of years older - I guess 76yo - but, unless I initiate the activity, he doesn't do it.

I have other friends in the late 60's and early 70's who went on a ride I led, but they were very clear they did not want to go over 'THE HILL" which - really is just a dimple on the landscape. But, they did not want to challenge themselves.

I don't have an answer, except that the wife and I (75 and 73) love exercising, and do it every opportunity we get. It is good we married each other!!