In 1998, Michael spoke out about his disease and the need for increased Parkinson's research. Since then, this father of four has become the voice for millions of chronically ill Americans and a vocal proponent of stem cell research.

Dr. Oz says people suffering from this disease can sometimes manage their uncontrollable tremors with medication…but not always.

"How much medication did you have to take in preparation for today?" Oprah asks.

"A boatload," Michael says.