It is no secret that Justin Bieber has had a rough past couple of years, from egging a neighbor's house to drag racing, but now the 21-year-old pop star is ready for his comeback, which includes the release of forthcoming album, "Purpose." Bieber's longtime manager Scooter Braun, as well as collaborators Skrillex and Big Sean, have all praised the young star for his comeback and his new, healthier lifestyle.

"I'll be frank," Braun told Billboard. "I failed for a year and a half. He shut himself off and went into a dark place. Every single day I tried to help him turn it around, and every single day I failed. And I tried desperately. The only person who deserves credit for this is Justin."

Producer Skrillex, who collaborated with Bieber on five songs off of "Purpose," voiced his shock with Bieber's turnaround and also praised his talent.

"A lot of times when he's not trying and just freestyles, some of the best s--t comes out," the producer said. "You got to hit record right away when he's, like, testing his mic, because the first idea is a lot of times the best idea."

Rapper Big Sean also echoed the thoughts of Braun and Skrillex, saying he was "building credibility as a true artist right before our eyes." The two have been friends since 2011, and the Detroit rapper is featured on a track from Bieber's upcoming album.

In his extensive and revealing cover story for Billboard, the 21-year-old also opened up about his ex-girlfriend Selena Gomez and suggested that people should be nicer to young celebrities, like Kylie Jenner.

Bieber's album "Purpose" drops on Nov. 13.