Justin Bieber: 'I am still striving to improve my behaviour'

Justin Bieber assured fans he is still working to improve his behaviour following his troublemaking years in an interview published days after his concert walkout.

The What Do You Mean? pop star vowed to become a better person when he launched his comeback earlier this year (15) after a long break from music, during which he became better known for his wild antics and run-ins with police.

Justin claimed he has changed his attitude, but his bad boy behaviour made a resurgence last week (ends01Nov15) when he stormed out of a concert in Norway because fans kept grabbing his legs.

In an interview with Britain's Telegraph magazine, which has been published just days after the incident, Justin confesses he has not completely let go of his bad boy self, but he is trying to improve.

"There's so much I need to work on. And I'm still getting days where I'm depressed and upset," he says. "But I know that I'm not where I used to be. So that really keeps me motivated. I'm not where I wanna be - but at least I'm not where I used to be... that's a cool little slogan I've been living by."

Speaking on his past behaviour, he adds, "I got so involved in 'me me me' - because you're young and people are telling you you're great all the time. And you start believing it... I started believing the hype and acting a certain way... I could feel people's energy, and I also really didn't care... And that's where things went bad.

"For a minute I was just too in my head, and I just wanted to quit everything... But I knew that was the easy way out. I know I'm meant for this. I know that God has a greater purpose for me to be in this position. It's just up to me to take that calling and respect it. It takes integrity to last in this business. It takes being a good person."

Justin apologised for the concert walkout on Instagram.com, telling fans he had "a rough week" with "long days" and "no sleep".