It all started with "the world's greatest undershirt."
That's according to Kevin Plank, CEO of athletic apparel company, Under Armour.
"When I began, it was just meant to be the world's greatest undershirt, just for football players, and quickly I found out it worked for baseball players, and lacrosse players, and the girlfriends of lacrosse players," he said. "It didn't begin as one massive vision but it began with being committed to one idea and making it the very best that I could."
Plank, the youngest of five brothers and a walk-on football player at the University of Maryland, said he grew up with a "massive" chip on his shoulder, which led him to develop a strong belief in himself.
It's this "I'm gonna show 'em" attitude that Plank thinks aspiring entrepreneurs should adopt.
"There will be moments that you will be alone, there are moments that you will be challenged, there will be moments you feel like you made the wrong decision," he said. "The only one who can make the best decision for your company is you."
During the initial struggle of starting a new business, focus and courage are the most important components for success, Plank said.
"If you have the right idea and the right conviction, it can work," he said.