I'm 52 and an equestrian professional. My Mum's 71 (closing in fast on 72) and rode her first Prix St. Georges last fall. My step-dad's 69 and a member of Canada's Nataional Para Dressage Team. My grandfather broke his last colt at 77, and rode into his 80's.
I have lots of clients in their 40's, 50's, and 60's. One of my clients is a 60 year old retired vet who's had both hips replaced, and she's competing at Fourth Level. Age is more a state of mind than anything else!
Talk to Heather Sansom about exercises to benefit your knee - leg strength and straightness will probably help. She made a huge difference to my back and hip issues (I've broken my back, and most everything else), and I'm now pain free as a result. Heather has a blog on this site, and she's happy to respond to your queries.
I was the poor kid who didn't have horses, but cleaned stalls to get to lead trail rides in Wpg in the early 60s. So I rode other people's horses for years - of course, those were always nuts or lame or unrideable, but quit for many years after a scary accident. I had a small child and felt riding (jumping) was too risky then. I returned to riding about 20 yrs ago when we moved to the country -Grey County - and bought my first horse when we bought this farm in 1993. I have 2 Canadians and a mini, and I ride every possible moment in the warmer weather - trail riding, popping over small jumps. I jump judge at Checkmate to get my wanna-be thrills. My intentions are to ride until I drop and i have the perfect horse for that, thank goodness.
I'm fast closing in on 65 and have been riding since about age 6 with formal lessons starting at 7 and continuing to this day. Although I've experienced hunter/jumper, western, saddle seat, side saddle and driving, dressage is now my passion of choice. If you have questions for your writing, please don't hesitate to write to me.