You are doing your kids a dual service by creating a time and place for fitness. Of course, you know the better shape you are in will lead to a healthier and longer life. You will be able to enjoy your children, grandchildren, and maybe even great-grandchildren IF you start taking better care of yourself and start exercising - NOW. Aside from being around to see your grandchildren grow, you will be passing down a legacy of fitness and nutrition to your children, who are being exposed to more physically inactive forms of entertainment than any time in history. Of course, consult a doctor before starting any program, especially with your kids. Children can exercise with running, swimming, calisthenics, and lift very light weights at any age. The rule is not to lift heavy weights until well into your teenage years (16-19).