Last month, I was lucky enough to spend an hour with one of the greatest entrepreneurs of all time, Richard Branson. Among much else, I learned one little-known aspect of the Branson origin story--namely, his boyhood inspiration.

That was one Douglas Bader, a Battle of Britain hero, Branson family friend, and possibly the most determined man of the 20th century.

Bader lost both legs in a flying accident in the 1930s. He not only taught himself to walk on artificial legs, without so much as a cane, but also to play scratch golf and to fly fighter planes well enough to become a top British ace. When Bader was finally shot down over German-occupied France, he lost one of his prosthetic legs. After his captors allowed a replacement to be airdropped to him, he rewarded their chivalry by promptly climbing out the third-floor window of his prison hospital and escaping.

It may not be exactly a straight shot from Bader's tin knee to the Virgin Group boardroom, but every founder needs inspiration. Branson took his from a boyhood idol. Many Inc. 500 CEOs tell Inc. that they got their inspiration from their father or close male relative. Cosmetics queen Bobbi Brown, for example, says she learned everything from her grandfather Sam Shatten, a Russian immigrant who became one of the most successful Cadillac dealers in Chicago."My grandfather taught me always to have your eyes open," she says, "because you never know what oppportunities are going to come your way."

For many entrepreneurs, of course, the inspiration comes from Sir Richard himself. No wonder: To launch his first successful company at the ripe age of 16, Branson overcame dyslexia, shyness (a problem he has clearly outgrown), and a doubting father who wanted young Richard to stop talking rubbish about entrepreneurship and become a lawyer like him. "Whenever you have an idea," Branson told me, "99 percent of people are going to tell you it won't work." In the end, young Branson decided, "Screw it; just do it," his five-word audible for making a leap into the unknown, as every entrepreneur eventually must.

Branson's history should remind you that even he once had nothing to go on but chutzpah and the example of a hero so indomitable that he refused to let a crippling injury keep him from what he loved. May that give you the inspiration you need--as we all do, from time to time--to screw it, and just do it.