Like most people in their 40s, Judd Apatow knows all about the sense of doom that comes with impending middle age. So who better to direct a comedy dealing with the issues surrounding one of life's biggest transitions than someone who has come out the other end still smiling?
"I think people at this age feel they are under pressure to do a lot of things at once," says Apatow of his latest comedy This Is 40, which centres around a husband and wife approaching a "milestone meltdown".
"They are trying to be perfect parents, take care of their extended family, deal with all this new technology . . . that's what I wanted to write about."
This Is 40 - Apatow's fourth feature film as a director - has been dubbed a "kind of sequel" to 2007's Knocked Up, starring Katherine Heigl as newly promoted TV presenter Alison who falls pregnant after a drunken one-night stand with slacker Ben (Seth Rogen).
Apatow says when he wrapped that film he never imagined revisiting the lives of some of his most popular characters.
Initially he wanted to make a sequel to his other comedy from the same year, Superbad, but couldn't get the cast together. So instead he chose to follow the lives of middle-aged married couple Debbie (Apatow's wife in real life, Leslie Mann) and Pete (Paul Rudd) - Alison's sister and brother- in-law in Knocked Up - as they both deal with turning 40.
Now well and truly in his 40s, and his wife having reached the milestone last March, Apatow admits the pair tapped into their own experiences - and those of their friends - when it came to penning the script for This Is 40.
"Lately I've thought of where I am as a (45-year-old) man. I don't know if it is a midlife crisis or a simple taking stock but I definitely have been thinking about how it is going," Apatow says. "You get to a certain age and you realise this is your life. You will not run hurdles at the Olympics or live on a mountain in Switzerland.
"This is my wife and family. This is my job and the rate at which I am going bald. Then you decide how you feel about it. I am generally thrilled with my life but at the same time, Leslie and I often wonder why certain aspects of our life and relationship are not easier.
"This movie explores those questions."
Indeed, This Is 40 shares a similar bittersweet tone to Apatow's 2009 film Funny People, which he wrote shortly after his mother died of ovarian cancer.
Like Funny People, which centres around a seasoned comedian (played by Adam Sandler) who learns he has a terminal and inoperable health condition, This Is 40 has just as many sobering moments as funny ones. In fact, it paints - as people approaching middle age will no doubt attest - a pretty accurate portrait of the challenges and rewards of marriage and parenthood in today's society, with Apatow exploring over a three- week time frame issues of sex and romance, career highs and lows, financial hardships, ageing parents and maturing children.
So how much of this film is based on fact?
"Our issues are very different because, unlike the couple in the movie, we are two creative people and our lives are a little bit of a circus," says Apatow, one of the most powerful and influential filmmakers in Hollywood.
"Leslie doesn't own a store and I don't own a record company . . . so the complications of our life are related to our creative efforts and the tricky effort of balancing working in movies and travel and our kids."
These days, however, the kids in question are almost as involved in the industry as their parents.
Apatow's two daughters - Maude, 14, and Iris, 8 - star in the film as Pete and Debbie's children Sadie and Charlotte, making it an almost complete family affair on screen.
The sassy siblings are no strangers to movies, having grown up on film sets, and both starred in Knocked Up and Funny People.
Maude is also a social media star in her own right, with more than 127,000 followers on Twitter (the subject of kids and social networking sites is of course covered in This Is 40).
This Is 40 marks the girls' first major roles in a film, though Apatow says they didn't need much coaxing to give convincing performances.
"There are some great natural moments between my kids that kind of only happened because they are actually having a conversation on film," he explains.
"And they are so comfortable that they can forget the cameras are there and just really debate any issues and mean every word they say. What (Maude and Iris) are arguing about in the movie is what they argue about in real life.
"They are five years apart so socially it's almost too big a gap to really enjoy each other.
"If it was bigger and she was a tiny baby it would be fun for Maude but the five-year age gap is annoying for the elder kid because the little kid wants to play with you and you are trying to be an adult with your friends.
"So that's been very tricky for them but playing out all their animosities in a comedy forced them to look at their relationship and realise how ridiculous it is and ever since we shot the movie they have gotten along a lot better."
And Apatow? I wonder how filming This Is 40 affected his relationship with Mann.
He admits turning the spotlight on what couples go through as they reach middle age forced him to take stock of his own life.
"For me, I write a movie just to figure out why I am writing a movie," Apatow says.
"That's my process. I know there are times when things feel funny and there are a lot of weird things happening in my house that make me laugh but it's not until the premiere when I watch it and think 'Oh that's what I was thinking about'."