do you have a horse now? what will your future riding plans be?
many of the muscles used in riding are not used for everyday movment. I remember when I started taking English riding lessons, at 41, I was exhausted after each one hour lesson. but, now, at 56, I have those muscles kind of in a baseline of fitness that I can ride without so much effort.
however, I find an hour of riding now to be a lot harder than at 46.
follow your hearts voice. take a few private lessons to get back into the saddle, so to speak