I have clients in their late teens and late 80s and everything in-between. What matters most is matching your fitness / health goals and current fitness / health level to the type of training. For instance I have a 75 year old that is fit and works out in the Small Group Classes. I have a 50 year old with painful joints that requires private training as they would not be able to get the kind of personalized attention they need from a group class environment.