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Roger Federer on his temper growing up: 'I was the opposite of cool'

Tennis star Roger Federer was a guest on Running Wild With Bear Grylls, in the Swiss Alps. While the winner of 19 grand slams was there, he opened up about the bad temper he had in the beginning of his career.

When Bear Grylls asked, "So did you have, like, your Roger Federer cool temperament when you were a kid?" Federer responded, "I was the opposite of cool."

Federer also talked about his bad habit of throwing tennis rackets early in his career. He talked about how he devised a way to throw the rackets into the net so that his parents wouldn't scold him for breaking another racket.

When Federer was 16, he got upset during a practice and threw his racket into the new backdrop of the National Tennis Center. The racket went through the backdrop like a "knife through butter." Federer's coach kicked off the court and made him scrub toilets for a week.

Realizing he had a problem, Federer spent the next two years focusing on his attitude and learning to combat his "fire" with "ice." He said, "You know like, have the fire and desire to win but the ice coolness to absorb losses and absorb bad mistakes."

Federer even attributed his great success to finally calming his temper. He said, "I realized, 'Okay, everything's clear to me now.' And then my career just went through the roof."

Running Wild with Bear Grylls airs on NBC. Visit the their website for air dates and times. Watch clips and full episodes for free on Yahoo View.