The 18-year-old singer admits he has experimented with alcohol but would never drink to excess. He said: "For me, it`s like I like to be in control of myself. I mean, I`ve had a beer, like, before... But I never get out of control." Justin`s manager, Scooter Braun, believes the `Boyfriend` hitmaker`s caution stems from his desire not to damage his career. Told about the star`s remarks, he told America`s GQ magazine: He knows that I hold him to a high standard... He doesn`t want to blow it." Justin - who is dating Selena Gomez - also admitted he struggles to trust people after having bad experiences in the past. He said: "I mean, I keep my guard up a lot, because you know, you can`t trust anyone in this business. "That`s what`s sad. You can`t trust anybody. I learned the hard way." The `Never Say Never` hitmaker also praised his friend Kim Kardashian for her strong work ethic. After a member of his entourage slammed an outfit she was wearing in a picture, he said: "You guys are so mean, bro... People say she doesn`t do anything; she actually does do stuff... She works hard."