Legendary investor and businessman Warren Buffett used to be so terrified of public speaking, he would become physically ill before taking the podium.
"You can't believe what I was like if I had to give a talk," Buffett recalls in the biography, "The Snowball: Warren Buffett and the Business of Life." "I would throw up."
But the young investor was determined to get over his crippling fear of public speaking and to woo Susan Thompson, whom Buffett would later marry.
So at 19, he enrolled in a public speaking course taught at Dale Carnegie, the institute named for the influential speaker and author of "How to Win Friends and Influence People" and other bestsellers.
After taking the course, Buffett was confident enough to speak in public and, perhaps more importantly, propose to Susan.
Today, would-be orators can hone their skills in the same class where Buffett developed his.
CNBC sat down with Joe Hart, president and CEO of Dale Carnegie, to discuss some of the most important lessons professionals can use to become better communicators — the same ones that that changed Buffett's life.