Sir Richard Branson has become an icon of entrepreneurship around the world, but the Virgin founder believes it all started by mistake.

"Like a lot of entrepreneurs, I was never thinking that I was going to become a businessman," Branson tells Inc. president and editor-in-chief Eric Schurenberg in an interview.

At the age of 15, Branson dropped out of high school and set out to give young people a voice, particularly around political issues like the Vietnam War. His very first business venture was a magazine called Student.

"My wish was to be editor, not publisher," Branson says. "But if you want to be editor and you want your magazine to survive, you got to get out there and sell the advertising and worry about the distribution. So in a sense I became an entrepreneur by mistake just in order to make the magazine survive."

Branson credits his enthusiasm for helping him sell $6,000 of advertisements over the phone to order a first print run of 50,000 copies. Student eventually grew to a circulation of 100,000. Its growth, Branson says, taught him a "fascinating lesson in the art of survival."

Shortly after, Branson began expanding his portfolio. In 1970, he turned the magazine into a mail-order record retailer. In 1971, he opened his first record store. In 1972, he opened a recording studio. In 1973, he started his own record label. The Virgin business empire had begun, and Branson had not yet turned 24.

Today, the Virgin Group is a global conglomerate of about 350 companies, branching into the entertainment, travel, and mobile industries. To hear more from Richard Branson on how the brand got started, watch the video below.