By Monica Rizzo
November 14, 2012 12:00 PM

For years Jillian Michaels was far from jolly around the holidays. “As a grown-up I was a bit of a Scrooge,” the trainer admits. “The trees make a mess. It always felt like I had to do so much stuff. I wanted to get out of town and go someplace unusual like Sydney or Thailand. Now it couldn’t be more different.”

That’s because, this year, her Christmas list got a little bit bigger: In May, the Biggest Loser star adopted her daughter Lukensia, 2, from Haiti and welcomed her son Phoenix, now 7 months, with her longtime partner Heidi Rhoades, 32. “I’m very anal in my old age, and my kids are breaking me of that,” says Michaels, 38, adding that this season at their L.A. home “we’ll go overboard for them—the trees, presents, lights, decorating, Christmas carols and parties. I don’t mind it now because I’m experiencing it through the kids.”

The new mom will even allow her kids to enjoy some of the traditional seasonal sweets. “It’s okay for kids to have treat foods on special occasions,” says Michaels, who regularly bakes homemade confections with Lu using applesauce instead of butter or oil and honey to replace sugar. “It’s a treat for her. When we cook, we say ‘pour that in’ or ‘stir that up’; she loves that. It really boosts her confidence.” Plus Lu gets to enjoy the end result. “I am going to allow my kid to have a cookie—not the whole plate,” says Michaels. “It’s all about moderation.”

But moderation goes out the window when it comes to Michaels’s excitement about her family’s first holiday. “Christmas Eve will be a big deal. We’ll get to open a special set of Christmas jammies, put cookies out for Santa and hang stockings,” says Michaels. Because she grew up celebrating both Hanukkah and Christmas, “we’ll do a tree and a menorah,” says Michaels. “We plan on exposing the kids to different religions and cultures, and then as they get older they can choose what feels right to them.” As for the clutter that comes with all the festivities? “I can suck it up because I know it will make my kids happy,” she says. “And when they’re superexcited, it makes me happy.”