If you ask most people to write down their assets they would probably list their bank accounts, retirement funds, real estate, etc., but I'm betting few would write down their body. Yet our body is, without a doubt, our most valuable asset.
My father, a heavy-weight boxer, always stressed the importance of clean living and a strong body. His advice becomes more potent with each passing year. With many of my friends and relatives reaching their 70's and 80's (some in their 90's), I can see first hand the value of protecting our most important asset. And the time to do it is not at those ages, but now--no matter how old or young you are.
When considering the keep of our bodies, there are several areas that are a must for aging well. In grammar school I had a teacher who was obsessed with the term input=output. Now, years later, I see how that simple equation fits into so many places. Food is one of them. Eating good, healthy food is a must to successful longevity. Exercise is another. The body needs to be pushed and used. A healthy mind is a big part of a solid future, and challenging ourselves mentally keeps us sharp and young.
No one can prevent random illnesses, but we can all ensure that we are giving our body the best chance to enjoy all its years. Starting young is smart, but starting is key. Even people in their fifties, sixties, and seventies can still make life changes that will benefit them for many years to come.
There's no preventing aging, but we can influence what the golden years look like, and they are only gold if we keep ourselves polished.