The summer of my junior year in college, I lived with the Huaroni tribe in a remote section of the Amazon rain forest, and that's where I met a shaman. Sitting serenely amid jars of his blessed botanicals and surrounded by his wife and their 18 children, he greeted me, looked into my eyes, and announced in his native tongue, "You are a very old man with the good fortune of inhabiting the body of a very young one." Despite all the mysticism surrounding the moment, I knew the shaman was right.

As a boy, I wanted to live to 100, even before I knew what a centenarian was. I've always attributed this to my close relationship with my grandparents, my fascination with the human body, and even Willard Scott's regular birthday greetings to 100-year-olds on the "Today" show. But, of course, getting to 100 requires more than mere optimism. Remaining healthy means a lifetime of making the best choices based on the best information.

A little background: My interest in the environment and public health is what took me to the wilds of Ecuador, but my wanderlust didn't stop there. I went to medical school in North Carolina, spent some time in Boston doing genetic research on (what else?) centenarians, and then moved to New York City for a residency in internal medicine followed by a fellowship to study geriatrics. Obviously, my medical training has given me the information needed to make healthy choices. But all of us -- no matter what our background -- still have to find our own motivation. I recognized mine when I chose a headline for this column. After all, living to 100 is vastly different from merely surviving to 100.