The problem with most people's knees is that they are obese to begin with. Knees weren't designed to bear that much weight.
SRH
My experience is just the opposite, the people who stayed active and involved with sports ran into knee trouble. I tore an ACL three years past at work, have not elected to have it repaired just yet. The other knee was injured in high school, torn miniscus and fractured cap, running track, which, ended right there, but, it didn't bother me in Golden Gloves. I did my road work a little slower, after freshman year, however.
I have trouble running, today, but, walk at least 2-4 everyday in the winter, and hold on in white knuckled fear when my Setter takes me for a bike ride, weather permitting. I ride my bicycles a lot. Still try to make The Lake Pepin three speed tour every spring.
Only meds are two asprins or Aleve on the bad days at work, those are typically thursdays or fridays when I've had to cut or throw paper into a press or folder. I walk out of the building tired!
But, I see it sneaking into my friends and family. I have more friends that have given it up, then friends that will take me up on an offer of a day hunting.
That, is the hell of it.
Best,
Ted