Blew my right knee playing HS football back around 1972. Knee surgery in 1974, where they removed my medial meniscus(the cartilage pad between the end of femur & tibia). Had multiple episodes of my kneecap dislocating (painful!) over the years, even after knee 'repair'.
Had my right knee replaced in 2017 - within 2 weeks, I was re-setting gateposts, and helping my wife pull a big dead calf out of a heifer (we had to do a fetotomy, cutting it up into several pieces to get it out). I'm sure that both of those efforts would have been frowned upon by my surgeon and physical therapist - but you gotta do what you gotta do.
Did the rehab religiously, and lost over 60 pounds in the process (got back down to what I weighed in high school, 40 years earlier). Within 2.5 months, I went to CA to visit my daughter and managed several 15-mile-plus day hikes (Dipsea Trail, Marin Headlands) with her.
Knee, pre-replacement was not especially painful, but really unstable. It's stable now, but range of motion is significantly less than in the other knee. 6 years out, it's still not 'my knee', but better, I guess, than before. Maybe if it had been painful before, I'd feel more positive about it.
When they were taking radiographs, pre-surgery, the Dr. said, "That other knee doesn't look much better than the one we're gonna be replacing." So... I may be looking at another replacement at some point, but I'm in no hurry to do so.
Got my money's worth out of my employer-sponsored health insurance that last year before I retired... knee replacement in January, left rotator cuff reconstruction with cadaver dermal implant in June, right rotator cuff reconstruction in December... retired Feb 1 of the next year.