I'm 65 years old and am recovering from surgery from a torn bicep tendon. And NOT from doing yard work for Christ's sake! From lifting a Skill Roll out of my van with just my right arm. THAT I will not do again!
I do yard work almost every day and get immense pleasure from it. I hope to be doing it at least into my 90's as my father-in-law did until last year at the age of 92.
I do not go up on ladders any longer though. Not too bad going up, but down was getting a little scary.