The evolution of Mann

This is 40 for Leslie Mann: mornings spent working hard to stay slim and youthful in a Brentwood, Calif., spin class; the rest of the day wrangling a curly-haired cherub, an irascible teenager, and a screwball husband who sends emails from the commode. That husband, of course, is writer-director-producer Judd Apatow.

And that husband’s latest comedy is This Is 40 (rated R, out Dec. 21), about a privileged, aging-phobic boutique owner (played by Mann) with a pair of overindulged daughters (played by the couple’s daughters, Maude, 14, and Iris, 10) and a music-producer husband (Paul Rudd) who’s secretly going broke and who can snag some alone time only by hiding in the loo with his iPad. So surely Mann was Apatow’s chief inspiration for the movie? This Is 40 is basically a home movie, right?

”I’m glad it feels like that, but it’s not, really,” says Mann, dressed comfortably in jeans, a sweater, and a puffy vest while imbibing inside a Santa Monica penthouse lounge with breathtaking coastal views that make her want to stay all day. ”It’s hard to explain. These are our characters from Knocked Up. But it’s not really a sequel.” She then catches herself. ”It is a little bit about us. We talk about the issues we may have, and then we let these characters play out the extreme version of us. Oh, I don’t know. I’ll have a sip of wine and think about that.”

In This Is 40, Mann’s character, Debbie, is the sun around which some very strange planets revolve, including an overenthusiastic trainer (Jason Segel) and a crafty, man-eating boutique employee (Megan Fox). Debbie wrestles with turning 40. She feels unappreciated by her husband, and with good reason — the guy casually exposes his derriere so she can tell him whether his anus looks weird. (Debbie’s response: ”Can we just keep a small shred of mystery in our relationship, please?”) ”I love that it’s not rosy like when you go and watch married couples in most movies,” says Mann, who’s quick to add that Apatow would never ask her for something as embarrassing as a butt exam. ”You usually leave feeling like something’s really wrong with your marriage because they seem like the perfect couple.”

Mann’s costars love the fact that she’s in it for the subtext, as well as the laughs. ”She takes what she does very seriously,” says Rudd, who especially likes the familial setting that comes with a Mann/Apatow set. ”She knows how to make something funny when it’s not funny to the character. She makes it very real.”

It’s the only way Mann knows how to work. She never actually eyed a career in comedies until she noticed that her fellow acting-class students tended to giggle during her dramatic scenes. (In a good way.) ”It seems like I just wound up in this world,” says Mann, who grew up with her mother, an older brother, and an older sister in Newport Beach, Calif. ”When I was little, my family said, ‘You know, when kids aren’t attractive, sometimes they grow up to be attractive,”’ she says. ”But I don’t see myself as pretty. My face is weird and long. I do weird things with my mouth and I have a weird voice. I’m just, like, weird.”

Mann met Apatow when she auditioned for 1996’s The Cable Guy, which he produced. ”After she left,” he says, ”I turned to the guy next to me and said, ‘I can’t believe the future Mrs. Apatow walked in and just sat down next to me. That’s so weird.’ Then the stalking began.” They married two years later. Mann went on to play a pretty jungle adventurer, a well-endowed girlfriend, and a childhood sweetheart in such comedies as George of the Jungle, Big Daddy, and 17 Again, and she also appeared in six of Apatow’s joints (including The 40 Year-Old Virgin, Funny People, and TV’s Freaks and Geeks). She’s not exclusive to her mate — professionally speaking — and he’s okay with that. ”I think we have a special thing together, but it’s just as much fun watching her in other movies,” says Apatow. ”There’s so much more she can do. I’m excited for people to see her carry a movie.”

Mann is refreshingly optimistic when it comes to finding out what her 40s will bring. Like most women of a certain age, she’ll kvetch about the aging process (”My skin, my hair … things are changing in me!”), but her milestone birthday wasn’t spent pouting; she went pole dancing with girlfriends in Hawaii. (”It’s hard! You have to have a lot of core muscles to do it.”) Mann’s equally open-minded about her future roles. She’ll play Emma Watson’s mom in the 2013 crime movie The Bling Ring and she has her sights set on something much more … pugnacious. ”I would love to work with someone like Quentin Tarantino,” she says, grinning. ”I would love to play someone who murders people with my bare hands, like some kind of, I don’t know, hitwoman.” Maybe this is 41.