Justin Bieber poses shirtless for magazine

Justin Bieber poses shirtless for magazine

Los Angeles: Pop sensation Justin Bieber has posed shirtless for the cover of Men's Health magazine.

The Canadian heartthrob, who just turned 21, shows off his muscular physique for the magazine's April edition.

Justin Bieber

In an accompanying interview, the singer opens up about reinventing himself and growing up.

"I do aspire to be a class act. This has really been a big year for me, as far as figuring stuff out. This is almost like a full 180 from how I was. Yesterday - a year from yesterday - I was in jail," Bieber said.

Bieber blamed his behaviour in the past year on the fact that he had to spend his teenage years in the spotlight.

"I had to grow up so quick. And it was almost like I grew up for the public but I didn't necessarily grow up," he said.

"There were things I had to do, as far as the way I had to make relationships and conversation, but as far as actually growing up, there were a lot of things I missed out on."