Gwen Stefani had the most beautiful thing to say about motherhood

'How am I gonna make sure these kids are good people?'

Words by Melody Chiu

From the editors of PEOPLE

She’s one of the coolest moms in Hollywood, but Gwen Stefani‘s younger self might not have thought so.

'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,’ ” the former No Doubt rocker, 47, tells PEOPLE exclusively. 'But you learn that when they have boundaries is when they feel the safest.'

A doting mom to three boys (with ex-husband Gavin Rossdale) — Apollo Bowie Flynn, 3, Zuma Nesta Rock, 8½, and Kingston James McGregor, 11 — the star struggles with setting limits for her kids like any other parent.

'The hardest thing to do is having a discipline chart and follow up on all those things,' says The Voice coach, who’s releasing a new doll line inspired by her hit Nick Jr. show, Kuu Kuu Harajuku, in the fall. 'It’s work, you know? But that’s where you get the results.'

As her children get older, 'I see a constant fear of ‘How am I gonna make sure these kids are good people?’'' Stefani adds. '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.'

While the Make Me Like You singer is enjoying her sons’ milestones, 'I love when they still play and you’re like, ‘Oh good. They’re still doing that.’'

She elaborates, '[But then] there will be other things like, ‘Can I get my ears pierced?’ I’m like, ‘Um, no. No, you can’t!’'

One of Stefani’s biggest challenges is also setting aside one-on-one time with each of her sons ('I think that’s super important they have that,' she says). But with all of her kids at home now for summer vacation, she’s also enjoying fun activities with them as a family.

'That routine of homework is just ‘Ugh,’' she laments. 'By the end, you’re ready to just have them be home and have a little bit more of a flexible schedule and do fun stuff that they love to do.'

And while she’s one of the most successful frontwomen of all time and in a high-profile relationship with country star Blake Shelton, at home she’s just 'Mom'.

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

The second season of Kuu Kuu Harajuku premieres Friday, July 7, at 7:30 p.m. EST on Nick Jr.

For more details on Gwen Stefani’s new Kuu Kuu Harajuku doll line with Mattel and her summer plans with her family, pick up the latest issue of PEOPLE, on newsstands Wednesday.