I had a thought on aging and health the other day.
What if hitting 35 flips a switch in the body that says the following:
If you continue to act young, you can still be so (more or less) for another few decades. But if you slow down (which is what I expect and why I flipped the switch), then you’re deterioration starts now. Being and feeling young by default has now been discontinued.
In other words, once you hit 35 you now must actively tell your body and mind that you’re interested in being young, otherwise it slips into “old mode” and begins deteriorating you.
But if you stay active both mentally and physically it seems quite content to simply continue on as if little has changed.