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The Backstreet Boys and New Kids on the Block ended 2010 on a high note with a rollicking New Year’s Eve mashup of their greatest hits in Times Square. But the guys still see room for improvement in 2011.

“I want to act more like an adult,” New Kid Joey McIntyre, 38, who will welcome his third child in May, told PEOPLE about his New Year’s resolutions.

“Being in a rock ‘n’ roll and pop world, it’s very easy to act like a kid. So, my resolution is to really act like an adult. It’s a personal inventory that I’m trying to take.”

Backstreet Boys Nick Carter, 30, and Brian Littrell, 35, will be turning over new leaves of their own. Carter’s resolutions? “Not to talk so much on the phone, and no texting while driving,” he says. “And I just want to stay fit.”

And Littrell? “To read more books and try to make better music.”

The two bands have been rubbing elbows ever since the Backstreet Boys made a surprise appearance at a NKOTB show at Radio City Music Hall last summer. Now, they have a whole North American tour planned together for summer 2011.

“We haven’t really explored everything about each other. We’re taking it slow and just being gentle with each other,” McIntyre says jokingly. “We get along really well. These are the best group of guys. We have a lot of shared experiences, and when we get together, it’s an amazing way to make a living.”

Asked which New Kid is most like which Backstreet Boy, New Kid Donnie Wahlberg, 41, replied: “You’d think it’s Joe and Nick who are the same and Donnie and A.J. [McLean, 32] are the tough ones. But if you are in the band, you know that every person is more than what they are perceived.”

Wahlberg adds: “A.J. is not the bad boy. He’s a sweetheart. And Joe’s not the young one. He’s wise beyond his years. There’s multi layers to everyone, which makes us all different, and that makes it great.”