We were in our 20's when my friend said 'A day in your 20's is worth a year in your 30's, a day in your 30's is worth a year in your 40's, etc...' Now in our 60's we're a little less adamant - every day is worth something.- but it has been a useful perspective.
Physically, I don’t feel a lot different than in my 40s. ( I’m pretty firm in my exercise schedule. ) But looking over almost anyone in their 80s, I’m reminded that the 60s likely kicks off ‘the fourth quarter’, to use sports parlance.
Time to let it all hang out, leave nothing on the table.
A day in my 20s was worth nothing. I went and flipped burgers for $4/hr, then probably went out for beers at a dive bar that night. Just living day to day.