Gwen Stefani may be a rock star but when it comes to her three sons, she's fairly strict.

During a new interview, the singer and coach of NBC's The Voice opened up about her parenting efforts for Kingston, 11, Zuma, eight, and Apollo, three.

“I was in a band and free my whole life, so I always thought I would be really free with [my kids] and do whatever I wanted, like, ‘Oh, I’ll take them out of school,’ but you learn that when they have boundaries is when they feel the safest,” she explained to People magazine on Monday.

Stefani shares three sons with Bush frontman Gavin Rossdale.

“The hardest thing to do is having a discipline chart and follow up on all those things. It’s work, you know? But that’s where you get the results,” she said.

“I see a constant fear of ‘How am I gonna make sure these kids are good people?’ ” Stefani continued. “I feel like naturally, it’s so easy for them to be naughty, and you get more and more worried about it the older they get... I love when they still play and you’re like, ‘Oh good. They’re still doing that.’ [But then] there will be other things like, ‘Can I get my ears pierced?’ I’m like, ‘Um, no. No, you can’t!’ ”

Although Stefani does her best to keep her sons on a structured schedule, she also enjoys the summer months when they have more flexibility.

“What I learned about having kids and having a career is [it’s] not all about us,” she added. “You realize that they only want you to care about them. It’s just that automatic, like, ‘You’re my mom!’ ”

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