Good for you! You have a made a decision to learn a fun and exciting sport that will keep you healthy and fit for the rest of your life. It is not uncommon to see people in their sixties and seventies on the trails these days! Physically, mountain biking is more like cross country skiing than road cycling. Both forms of cycling are low impact but mountain biking also involves some upper body strength so it is a good all body workout that is so much more fun than a stationary bike! And there are no cars and trucks to worry about!