If you’re not already envious of Jason Segel, 34, for his massive films (Forgetting Sarah Marshall, The Five-Year Engagement), and hit TV sitcom, How I Met Your Mother, now in syndication after nine seasons – then consider this: in his latest film, Sex Tape, he spent three full days shooting steamy scenes with Cameron Diaz in which they tried every position in The Joy of Sex, as the script demanded – a script Segel co-wrote. "OK, that’s fair, you’re allowed to be jealous," he laughs, folding his 6ft 4in frame into an armchair at the Beverly Hills Four Seasons hotel. "And the best part was it didn’t even have to be sexy! Because that would have made me nervous. Having to have a ‘masculine allure’."
They play a married couple whose sex life has waned after having kids. In an effort to get their groove back, Diaz suggests they "make a porn", which then leaks and a caper ensues to stop it getting out of control. Like many Segel films, it’s a soft-hearted romcom with a mushy moral about love and relationships. And he’s right, it’s not sexy – it’s goofy, silly and almost devoid of sizzle, even though both leads are naked for long stretches.
"I’m OK with nakedness," he shrugs. "Bottomless is no harder than topless. I have no shame. So, yes, that’s my butt up there, I didn’t employ a double. And I never will!"
He didn’t go the full Fassbender, though – it’s not that sort of film. "For those scenes, I wear a dangling sock over my junk," he explains. "But that’s out of respect for your acting partner. I might not be embarrassed, but you have other people to consider!"
To be accommodating and inoffensive is important to Segel. He’s a man of manners and respect. There’s something old-fashioned about him that way. For this interview, he shows up on time, answers every question earnestly, talking in a measured and gentlemanly fashion like an old broadcaster, always in full sentences. And no swearing. When I quote his movie’s "teachable moment", a line about how sex tapes are made by people "who forgot why they were fucking in the first place", he squirms: "I don’t want to quote the line myself, because it’s so vulgar. As a character, it’s fine, I just don’t want it coming out of my mouth as Jason Segel."
It’s this wholesomeness that distinguishes him from his peer group, that school-of-Apatow batch of unorthodox leading men who have become actually quite orthodox over the last decade – the likes of Jonah Hill, Seth Rogen and Paul Rudd. Of them all, Segel is the traditionalist, the grown-up, the most conventional. While Rogen and Rudd often play rogues who party and get high, Segel’s best known characters are in the classic romcoms that he writes like Forgetting Sarah Marshall and The Five-Year Engagement – sensible young men who are looking to settle down, but fumble on their way.
He’s nostalgic at heart. Ask what his favourite romantic comedies are, and he looks back to the New Hollywood era. "The reason Broadcast News and Annie Hall are so brilliant," he says, "is because the couple doesn’t end up together at the end. You can’t pull that kind of thing off anymore." He became obsessed with remaking The Muppets (from the Seventies), and did so brilliantly, with the film winning an Oscar for Best Original Song. And when we discuss why audiences have connected with everymen like him and his peers, as leading men, he harks back to the Forties. "There are two kinds of movie experiences you can have," he says. "One is wish fulfillment, and the other is where you feel you’re watching yourself up there. That’s what Kermit the Frog and Jimmy Stewart did so well."
Like most of the Apatow gang, he grew up in LA and started young, as a teenager. He was 17 when his mentor Apatow cast him in Freaks and Geeks. And but for a few fallow years just after, Segel has risen quickly, propelled by an intense ambition. He was cast on network sitcom How I Met Your Mother and took every opportunity to make movies in between seasons.
"I thought, to maintain my status, I should make one film a year at least," he says. "So, I’d write it through the year and shoot during that April-to-August hiatus from the TV show. It was a real hamster wheel."
They were heady years. He lived behind the Chateau Marmont on Sunset, so close the hotel offered him room service. Apparently, his house was once home to Charlie Chaplin, though now, he suspects that’s what LA estate agents tell everyone. It was just Segel and his Muppets, which he kept on display, until it dawned it wasn’t doing him any favours with girls.
But those days have passed. His sitcom wrapped last year, and now he’s going through that midlife celebrity moment in which the young star understands fame and money aren’t everything. And being the old soul he is, this is all happening at 34.
"As I’ve grown older, the things I care about have narrowed," he says. "I’ve realised that this business constantly tightens the criteria for success so that you’re never winning. Turn around and there’s another billboard with another guy whose movie made a little more than you, or this guy’s doing this kind of movie that you wish you were doing."
So he’s all about transcendental meditation now. No more hamster wheel. Admittedly, Sex Tape hasn’t wowed the critics, however much fun it was to make – maybe a film about homemade porn by the guy from The Muppets was a bit of a left turn. But there are experiments afoot – unlikely departures for a talent like Segel.
The End of the Tour comes out soon, a film in which Segel plays the author David Foster Wallace, who famously committed suicide. "It was a total honour," he says. "I’m really interested in acting the kind of material I’m not able to write."
He’s also trying fiction and later this year, his first book is published. Nightmares, for children, is based on a screenplay he wrote in his twenties and sold to Columbia Pictures, but never got made. "I waited for it to go into turnaround, when it becomes available again, and I bought it back, for the amount they bought it for."
Is there anything else in his vault he might adapt? He lights up, the ambition’s still there, you can tell.
"So far, everything I’ve ever written has had something happen with it, except for two things Nightmares was one of them, and now that’s a book. So, there’s this one last script.” He laughs. “I can’t help it. I’ve got this Count of Monte Cristo-esque thing, that says, ‘Let’s go revisit those and turn them into something!’"
Sex Tape is out now
Photographer’s assistants: River Jordan, Andrew White | Stylist’s assistant: Nathan Unce | Grooming: Jamie Taylor at The Wall Group using Tom Ford i car: 1969 porsche 912 | Motorcycle: Deus Ex Machina Boodaak | See stockists page for details