The 21-year-old star admits she pushes herself hard in her work but no matter how tired she ends up feeling, it becomes worthwhile when she goes out on stage and sees her audiences.
She said: "I don't feel like I can do enough for my fans. I work a lot, I work hard, and I get tired. But when you walk onstage and see these people who wait hours outside just to see you, it's the greatest thing in the world."
The brunette beauty - who has an on/off relationship with Justin Bieber - is pleased to have "supportive" friends, even when they don't take her side in arguments.
She told the new edition of Seventeen magazine: "I noticed my friends were different, that we were all becoming supportive. I'd get so angry at a friend and tell another friend and she'd just say, 'Why don't you look at her side.' And those things p**s you off in the moment, but then you realize that that's who you want to be surrounded by."
The 'Come & Get It' singer is close friends with Demi Lovato and Taylor Swift and appreciates their friendship as she knows they will never be too busy with boyfriends to spend time with her.
She said: "Some girls will drop you in five seconds for the right guy. That's not how it's supposed to be. That's why I love Demi and Taylor -- they support females and love to have that empowerment! I wish girls would stop hurting each other."