Tennis can be bad, I screwed up both my knees on that sport. At first the arthritis specialist thought it was rhumatoid arthritis, but another Rhumatoligist said I physically or mechanically screwed up the bones in my knees. Since we are on the subject I've had two hernia operations, surgery on my finger tendon, and a .22 cal bullet richochet removed that lodged in my right bicept! Oh yeah, I have a hearneated disc (L4) that will eventually need surgery. At least I don't pay for it in Canada, thank God!!
On the Arthritis, I first developed a virus that caused it in Sept. 2000, and it basically left me paralyzed for two months, Ive got pics to back that up. I know what you mean about the pain involved just to lift your arm to type or reach for the beer!