"I only gained 23 pounds when I was pregnant, and I'm still 10 pounds heavier, but I don't want to kill myself trying to get back into shape because it's not a priority right now," she says in the Dec. 7 issue of the U.K.'s Daily Mirror. "I'm too in love with Noah, and I don't want to be away from him. I just want to be home."
Fox, 26, also explains why she and her husband, Brian Austin Green, 39, recently decided to hire a nanny. "Having an infant is difficult. It's a lot of work, and I didn't hire any help because I overestimated my own abilities. I had no idea how difficult babies could be, so Brian and I were exhausted," the star of "This Is 40" says. "You never sleep and you're awake all night, and your entire life is devoted to this little thing that needs you constantly. And I love it. It's what I've wanted to do since I was a little girl."
The new mom continues, "I always wanted to mother things, and I constantly had a doll I was taking care of. I don't receive the same satisfaction from my career as I do from being a mother, so I'm really happy. But two weeks ago I said to Brian, 'We have to get a night nurse or we're going to get a divorce, because someone's got to sleep in this house or we're going to kill each other.'"
Fox -- stepmom to Green's son, Kassius, 10 -- tells the Daily Mirror that she'll be shying away from sexier roles now that Noah is in her life. "It changes your perspective about being overly sexual in a film when you have a baby. I'm going to be more cautious about choosing films because I'm already thinking about when he's in school and his friends are going to be showing him my photo shoots with me in a bikini, and he's going to be horrified," the actress says. "So that will deter me from making some of the choices I made before."
Of course, Fox's wild days are far behind her. "I went through a stage in my early 20s when I was very rebellious against how I was raised, and I wasn't worried about faith or religion," the "Jennifer's Body" star admits. "But now, maybe because of getting married and wanting to have a family, I've come back full circle."