Actually tennis is a great sport, but it can be very tough on knees. And long distance running? My uncle is a world class marathoner who had both knees replaced at 50. Both are non-contact.
True that’s why I prefer clay. Preserves the knees.
It also doesn’t compare to a 250lb linebacker spearing you in the side of the knee. That absolutely shatters em.
Kudos to your Uncle. I was a sub 17min 5k’er in High School so I know how rough that is on the body. Running may the most mentally-challenging and physically painful sport ever invented.
Don't play on hard courts.