I'm 38, soon to be 39, and other than a few creaks and aches now and then, I feel great. I love the challenge of Cathe's workouts! I've tried less intense instructors, but I get bored so easily and don't feel like I'm getting a good workout! I must say, I'm glad she's doing more low impact, as that's where I'm afraid I'm going to struggle as I get older. (bad left knee)