Under Armour's underdog strategy to becoming the anti-Nike

Nike has ruled the sportswear sector for years.

But Under Armour has slowly been eating into Nike's market and is now the second most-popular athletic apparel brand in America. Adidas lags behind at number three.

The brand's secret to success isn't to imitate Nike's strategies. Instead, the brand focuses on what makes it different to drive sales.

Under Armour marketing executive Adrienne Lofton told Fast Company that the brand considers itself an "underdog brand."

"We work with athletes who most people wouldn't or didn't draft in the first round, or who they wouldn't traditionally give a prima ballerina title to. We pick that athlete with a chip on their shoulder and their desire to win because it aligns with our own attitude," she told Fast Company.

For instance, Under Armour partnered with Stephen Curry (a deal that has been paying off tremendously) - someone whom she says rose to success "because he trained every day, got up when he fell down, continuing to drive with all that unsexy work to achieve his goals."

And Misty Copeland, a star dancer, is an alternative choice - dancers face many obstacles en route to success.

Consider this the "anti-Nike" approach.

Nike is known for partnering with some of the most successful athletes out there - look no further than its partnerships with LeBron James and Michael Jordan. And Nike's iconic tag line 'just do it' is certainly a strong call to action, denouncing excuses completely. But what about after you've started the process? And what if 'just doing it' isn't so easy after all?

That's where Under Armour comes in.

"A lot of brands are about that initial motivation - just do it, get up, and go - we talk about how sustaining that effort is what makes the difference for an elite athlete, and we want to be the brand to show you how to do it," Lofton told Fast Company.

That said, Under Armour has certainly not had a shortage of stars partner with the brand, including Tom Brady and Gisele Bündchen, all of which have likely helped to contribute to the company's growth.

This mentality is certainly paying off. The brand is becoming a competitor not only to Nike, but also to Lululemon with its athleisure line for women and its coinciding empowering catchphrase, "I will what I want.

Rather than focusing on being aspirational or simply inspirational, the brand focuses on conveying the message that you must work hard to achieve your goals - a methodology that certainly sees benefits, whether you're an athlete, a businessman, or a sportswear company from Baltimore.