When I was younger, I always wanted to jump on horseback. In grade 8, I ended up banging up my knees badly and was told not to play sports for a week ( I did anyways). Since the last 2-3 years, I have horrible sharp pains in my knees and was told I have the knees of a 80 y/o woman. I have arthritis.
So I can't jump long enough anymore without feeling pains in my knees. Dressage is now something I like doing. =]