Nick Carter tells Us Weekly he is "excited" to join the cast of Dancing With the Stars Season 21. Credit: Charles Sykes/Bravo/NBCU Photo Bank

Fifth time's the charm! Nick Carter reveals exclusively to Us Weekly that he has signed on for Dancing With the Stars Season 21 after four years in a row of offers from the DWTS crew. "I'm excited," he dishes in Us Weekly's latest issue.

And the person who talked the Backstreet Boys singer into signing on the dotted line? None other than former boy band rival-turned-friend, Joey Fatone, who participated in Seasons 4 and 15.

"He talks about it all the time and I was really debating if I wanted to do it, and he said, 'It's a great experience, it keeps you in shape and it'll teach you a lot of stuff,'" Carter says of his 'N Sync pal's advice. "He said, 'You'll get what you put into it.' And I'm a hard worker, so I think it'll be fun."

Another reason he wanted to do the show? Sibling rivalry. Carter's little brother, singer Aaron Carter, finished in fifth place with partner Karina Smirnoff during Season 9 of the ABC hit.

"My brother was on it; he did great; and he's a great little dancer and entertainer so I saw it through his eyes throughout that experience," the elder Carter brother reveals. "And there's a lot of competitiveness in me and I think there's a little something inside of me that says, 'Okay, I'm going to go there and represent the Carter name and do even better than what he did!'"

Interestingly, although Nick has danced with his BSB bandmates for more than two decades, he's a little shy about his dancing skills. "I never considered myself a great dancer. Even though funny enough I've danced my entire life, I might have had a little insecurity on that end. But I felt this time around I had some time and I think it'll be a cool experience. I think they can teach me some stuff."

He adds, "I hope maybe I can become a better dancer! It'll be a great experience to learn how to ballroom dance."

Nick also hopes his quest for the Mirrorball Trophy will do wonders for his fitness. "I have a tendency to get overweight pretty damn fast," he confesses with a laugh, "so dancing has always kept me slim." 

The boy-bander joins already announced castmates Bindi Irwin and triple crown jockey Victor Espinoza, along with returning pro Smirnoff. Find out the rest of the cast when the celebs and their partners are revealed Sept. 2 on Good Morning America

Dancing With the Stars premieres Monday, Sept. 14 at 8 p.m. ET on ABC. 

Can't get enough of Us? Sign up now for the Us Weekly newsletter packed with the latest celeb news, hot pics, and more!