I hear you Jane on the arthritis of the knee, my mom has it, her mom had it before her. Already realizing I can't do exercises that strain the knee excessively like squats, but that's just "hey stupid, don't do squats, your knees aren't built for that". My mom is otherwise she is quite healthy at her age - in her 80s - she's either got many years ahead or will go in near perfect (except for the darn knees) healthy probably.