Justin Bieber doesn't own a cell phone

He said: “I definitely learned how to have boundaries, and I just don’t feel like I owe anybody anything.

"That has helped me to be able to just say no and just be firm in it and know that my heart [wants] to help people, but I can’t do everything. I want to sometimes, but it’s just not sustainable.”

The 'Yummy' hitmaker has made other changes to his life, including attending therapy regularly and reconnecting with his faith.

He told Billboard: "I just changed my priorities so that I didn’t [become] another statistic of young musicians that ended up, like, not making it."

And now Justin wants to use his fame and his music to "inspire" other people.

He said: “There was a time where I really did have my identity wrapped up in my career, but I really do have an overflow of feeling like my purpose is to use my music to inspire...

“I just want to be somebody who can say, ‘Look, I did some things that I’m not too proud of, but I took a look in the mirror and decided to make some changes, and you can too.' "

The changes the 'What Do You Mean?' singer has implemented in his life have been welcomed by his management team.

SB Projects president Allison Kaye, who co-manages Justin with Scooter Braun, said: "This is a kid who I used to have to beg to go to a rehearsal.

"We used to have to take his computers away or put someone outside his door so he couldn’t sneak out.

“He’s not even becoming a boss — he’s becoming a leader. It’s such a beautiful thing to see out of someone whom you’ve known since he was, like, 12.”