Kate Winslet Reveals Her Kids Encouraged Her to Make Avatar Sequel: 'You Have to Do It!'

Kate Winslet doesn't normally involve her children in any career decisions, but when the topic of joining Avatar: The Way of Water came up to sons Bear, 9, and Joe, 19, and daughter Mia, 22, the actress discovered a few surprise Avatar superfans in her midst.

"I was just super happy to jump [into the world of Avatar] and very excited to be asked," Winslet, 47, tells PEOPLE of getting the initial call from director James Cameron in this week's issue. "He called me and described the role and I thought, 'My God, that sounds amazing.' And my kids were like, 'Oh my God, mom, you have to do it.' I was like, 'Obviously.' I said, 'Well, they're going to send the script.' They were like, 'No, it doesn't matter. Just you have to do it!'"

In addition to having her kids' blessing, the role in the highly-anticipated sequel also offered the Oscar-winner an opportunity to reunite with her Titanic director, with whom she's kept in touch since the release of the 1997 smash hit.

"We've totally kept in touch over the years. He's very good at Christmas and birthday presents," Winslet says of Cameron. "He always remembers. He's amazing."

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And although she was a newcomer to the franchise, Cameron and Winslet's castmates have praised the Oscar-winner's mastery of holding her breath underwater — training which the actress took very seriously and incorporates in her real life today and with her family.

"I have a lot more interest in breath work now for sure. And it is very calming," she says. "But I certainly do [still use it]. If we are on vacation, for example, and one of the kids will say, 'Oh, I'm going to dive down and get that shell.' I will say, 'Okay, not too deep please.' I know how deep they could safely go before they need to come back up and take a sequence of specific breaths on the surface to not get that kind of slightly stars-in-the-air blackout feeling because that's when actually people run into trouble, when they surface [too quickly]."

She continues: "There's a breathing sequence and I make them do it now. I surfaced from [holding my breath] for seven minutes and 15 seconds. I was trained so well and I had all the safety in place and really respected the process. You can't muck around with it. And it isn't something you can just do at home. And you must do it with another person there. So it was just amazing, honestly. It really was an extraordinary thing to learn."

Avatar: The Way of Water opens in theaters Dec. 16.

For more on Kate Winslet and Avatar: The Way of Water pick up the latest issue of PEOPLE on newsstands Friday