When chess prodigy Magnus Carlsen was 13 years old, he squared off against chess grandmaster Garry Kasparov, one of the world's top-rated players. As Carlsen sat down to spar, he couldn't shake the feeling that he couldn't possibly win against such a formidable opponent. Now 27 years old, Carlsen says giving in to that belief was his biggest mistake.

"In that particular game if I [had] actually believed very seriously that I could [have] beat Kasparov, then I probably could have managed," he says. In other words, skill will only take you so far; confidence was the missing piece he needed to beat his opponent.

In business, too, there are plenty of ways in which you might face similar crises of confidence, whether it's making a pitch to investors or trying to win an account with a big customer. Here are three tips from Carlsen on how to manage these moments and build self-confidence: 

1. Trust yourself, no matter the consequences.

Confidence comes from trusting yourself to make a decision and being OK with the results, even if you fail. This explains why so many successful entrepreneurs count failures on their lists of achievements. For Carlsen, this meant trusting his gut and making a fast decision -- and then not looking back. "It's better to trust your gut and be burned sometimes than to always second-guess yourself," he says.

2. Be willing to put in the work.

By the time Carlsen was 17, he was playing the best chess players in the world -- and for the first time, he says, he started to feel confident in his abilities. "When I was 10 or 12 years old, I would often give away draws to presumably stronger opponents because I didn't actually believe that I could beat them and I was happy with a draw," he says. Of course, he had many matches during those intervening years, which helped him improve his skillset, and thereby his confidence. 

This kind of self-doubt is often referred to as imposter syndrome -- a psychological pattern in which you doubt your own accomplishments or believe that you don't deserve them. To overcome this, as Carlsen did, you must first recognize the condition and then work diligently to overcome it. As Carlsen says: "Within a few years I was completely convinced, rightly or not, that I was the man, I was the best."

3. Look for an immediate win after you lose.

Carlsen's approach to losing is also instructive. When he loses, he says he doesn't dwell on it because bad results can linger. Instead, he looks for a win -- as soon as possible. "For me I just... need to somehow be able to strike back," he says. 

He also notes that he's never been a good loser, and that instead of working on ways to handle losses more gracefully, he focuses on a different problem: "I should be better at not losing."