Kim Williams, MD, is past president of the American College of Cardiology (ACC).

Let's take a moment to appreciate how amazing that is.

First of all, he grew up poor and black on the South Side of Chicago. One winter he ended up in the hospital with pneumonia; his family couldn't afford to buy him a coat. His step-dad died of an intercranial hemorrhage when Kim was five years old.

Second, Dr Williams chose medical school over a promising career as a professional tennis player.

Third, he's the first and thus far only president of the ACC to "come out" as a vegan. The current chairman of cardiology at Rush University Medical Center in Chicago has been vegan himself since 2003, and now recommends a vegan diet to his patients as the first line of defense against heart disease.