The fountain of youth might be a myth, but with the almost daily advances in medicine and health care, breaking the century mark is an attainable goal for many people. By the year 2050, America will be home to an estimated 1 million centenarians. In fact, you may already be well on your way.
Live an active life, both mentally and physically. You don't have to be an exercise nut, but keep moving. Walking, golfing, swimming-- anything at all is good. Implement a stretching program to maintain your flexibility and lift weights to build muscle and prevent osteoporosis.
Stay married. Numerous studies indicate that married people live longer than single people. There's the old joke that it just seems longer for married people, but in reality it seems to help.
Maintain your ideal weight. Being overweight will definitely limit your chances of becoming a centenarian and is likely to make the journey a slow and painful one.
Drink moderately and don't smoke at all.
Have good genes. Extreme long life seems to run in families and may be based on common genetic and environmental factors. If you have a centenarian sibling, your chances of living past the century mark increase greatly. (Of course, you're probably pretty old already yourself.)
Eliminate unnecessary stress as it shortens your life. Finding satisfying, meaningful work is likely to contribute to a long life, and certainly does to having a life you enjoy. If you're retired, do something that gives purpose and value to your life. See 14 Balance Home and Work and 16 Set Goals.
Develop close and respectful relationships with your friends and loved ones. This may actually be harder than living for 100 years, but it's a big help if you can manage it.
Live simply (see 15 Live With Less). Huck Finn probably lived to 100 because he understood that today is what counts, fine clothes are itchy, and money is a burden.