It all started with a shirt.

Kevin Plank, a University of Maryland football player, wanted to practice and play in something a little more high tech than cotton. He was tired of wet, soggy, thin T-shirts--he needed something that would keep him dry but not weigh him down as an athlete. Seven prototypes followed. The most impressive iteration was made of lightweight polyfibers and didn't hold on to moisture; it also applied compression--which hadn't yet been done. It became the staple Under Armour T-shirt.

Sixteen years later, the desire to continue to create something better than what exists has led Plank's sportswear firm to project a 2012 net revenue exceeding $1.78 billion. Plank is Under Armour's president, CEO, and board chairman. He has led the expansion of the Under Armour brand into a wide array of kinds of athletic apparel, as well as street-wear shoes and accessories.

It's easy to forget that not so long ago, Under Armour wasn't a household name. Here's how Plank took his company from left-field idea to mainstream brand.

1. Solve Real-World Problems

When you work out, you sweat. When you sweat, your clothes get wet--and then you're stuck in them. To Plank, this was a problem. So, he says, he found a solution. "Our job is to be smart enough, to be humble enough, to identify what's happening out there in the world and what are the things we can do to make it a little bit better," Plank says. He worked to make Under Armour an aspirational brand--but not one that's too out of reach for average consumers: The brand's self-stated mission is to "empower athletes everywhere."

2. Stay Focused on a Single Mission

On a whiteboard in Plank's office, a simple message helps him not lose sight of his initial goal: "Don't forget to sell shorts and shoes," it reads. In other words: Never lose sight of your primary goal. It was a steadfast focus on this goal that enabled Plank to start his business in 1996--and then for its growth to reach rocket speed. By 2003, Under Armour was No. 2 on the Inc. 500.

3. Believe in the Power of Other People

When Plank started Under Armour, he had $17,000 in cash and $40,000 available on credit cards to fund the company. "[I was] smart enough to be naïve enough to not know what I couldn't accomplish," he says. But Plank says not knowing how quickly he could burn through his funds made him take the entrepreneurial leap of faith and learn the value of the people who believed in him.

Incredibly grateful to those who helped him get started, Plank launched a fund at the University of Maryland to finance budding entrepreneurs. "We can get caught up with all the things we can't do, but I encourage people to believe," Plank says. "Optimism is a free stimulus--so why not us, and why not you?"

4. Trust Mom

When Plank spoke at National Small Business Week in Washington, D.C., he brought along his mother, Jayne H. Plank, a former mayor of Kensington, Maryland. Karen Mills, Small Business Administration administrator, approved, saying as she introduced Plank: "Anybody who brings their mother along is OK by me." But Plank had more than a polite reason to bring his mom along. It was she who introduced Plank to some of his most valuable initial relationships. And--as many entrepreneurs' mothers have at one time or another--she provided some funds for his fledgling business. "Any self-respecting entrepreneur has borrowed money form their mother at some point," Plank says.