Dr. Michelle Johnson's journey into medicine has been both ironic and bittersweet. When she lost her dad to heart disease and, years later, watched her mom -- who had successfully battled breast cancer -- get stricken with pancreatic cancer, she couldn't imagine being anywhere near a cancer-treatment facility. But Johnson, a cardiologist who now works at Memorial Sloan-Kettering Cancer Center in New York City, decided that in honor of her parents, she would commit her life's work to help prevent the spread of these deadly diseases. Her latest contribution is to 'The Black Woman's Guide to Healthy Living,' presented by the editors of Essence magazine, in which Johnson and several other physicians, counselors and experts contribute their wisdom and knowledge to help black women get, and stay, healthy.

According to a recent study by the National Center for Health and Statistics, more than 34 percent of all Americans are obese. We're not just fat or overweight -- but we're obese! And as the saying goes, when America has a cold, black America has pneumonia. More than 53 percent of black women fall into the category of obese!

"And worse than that, blacks in general lead just about every negative category as it relates to health -- from the rate of diabetes to heart disease to high blood pressure," says Dr. Ian Smith. "The main culprit: obesity and diet."

Instead of watching folks die and continue a life of disease and poor health, Dr. Ian has been, for the past few years, involved in making a difference. He launched a 50-million pound challenge to Americans and he travels across the country helping people lose weight. To date, more than 825,000 people have joined the challenge and have collectively lost 3.1 million pounds.