The woman was 65-years-old, "maybe a little older," and actor Josh Brolin had not met her prior to their introduction at the drinks party they were attending. Still, the woman leaned in and said quietly, "Thank you for rekindling my libido." Now, that is not a line I've ever had whispered my way at a drinks party and I wonder how Brolin reacted to this stranger's intimate gratitude? "I thought it was hilarious," says Brolin, "and the fact that she said that about a guy who's meant to have been in prison for 19 years, or whatever it is, is even more hilarious." The guy who's meant to have been in prison is the guy that Brolin plays in his latest film, Labor Day, in which he stars as an escaped convict who strikes up a tender relationship with a single mother, played by Kate Winslet, and her only son in a small American town.
It is a film aimed primarily at women the same age as the drinks party libido lady. "Honestly," continues the 46-year-old Californian, "putting the humour aside, that woman had a profound experience in the theatre and you want the audience to have an emotional experience while watching the film.
"I'm a geek for that," he adds. "I can see a horrible film, and still laugh and cry and then walk out and know I didn't like it that much. When the lights go down I lend myself to it completely because I love that experience."
His latest film has not proved popular with the critics – clocking a lowly 33 per cent average on the review aggregating website Rotten Tomatoes – and took less than $15 million at the American box office when it was released earlier this year.
"It is generated towards a demographic that I'm not used to," he says of the movie. "So when I have a 65-year-old woman say to me, 'Thank you for rekindling my libido,' that is one of the greatest things that I've heard in my whole life. It means the film's had a profound effect on someone."
The film was a rare leading man role for Brolin, whose more critically endorsed work has come courtesy of supporting roles in films like No Country for Old Men, Planet Terror, American Gangster (all 2007), Milk (2008) and True Grit (2010).
Even his rare blockbuster outing in the 2012 sci-fi comedy Men in Black 3 – starring as a young version of Tommy Lee Jones's stony-faced character – was a secondary role to Will Smith's highly energised agent.
"It's not that I shied away from being a classic leading man," says Brolin. "I just didn't always get it. Men in Black is a perfect example.
"It is a quintessential blockbuster, but it's a great character and a character that scared the shit out of me. I know Tommy and I never thought that role was something that I could pull off.
"But then I thought, what does that mean? Why couldn't I pull it off? What if I could – it could be a great challenge, like an experimental theatre piece, and if I fail then I fail, at least I tried.
Brolin's words of wisdom more usually fall upon his two sons, Trevor and Eden, whom he had with actress Alice Adair. He was once engaged to Minnie Driver and up until last year was married to Diane Lane. The couple wed in 2004 though she subsequently filed for divorce.
"That is what I now always try to teach my kids – you don't know until you try," he continues, extolling the virtues of persistence. "The whole 'I'm not ready thing' doesn't really exist. You don't know if you're ready until you do it.
"If it doesn't work out, then you're not ready but if you're impassioned enough you'll do it again and then you might be ready. You don't know until you try."
Brolin has certainly tried some brave career moves, last year starring in Spike Lee's American remake of the violent South Korean thriller Old Boy, which met with a lukewarm reaction, while previously taking on the role of George W Bush in the 2008 Oliver Stone-directed biopic W.
"Playing W didn't help my career at all," he says of the film, "but that wasn't the point. We got into how a guy like this got to be President twice, why everyone wanted to sit down and have a beer with him; why everyone wanted to give this guy a break, without judgment. That was interesting to me."
If he'd managed his career differently, Brolin says, he could have enjoyed more financial success. "I could have more money," he says, before laughing: "I wish I had more money."
He grew up around actors. His father James Brolin was a big TV star in the 1970s courtesy of shows like the hospital drama Marcus Welby MD. His parents divorced when he was 16-years-old and his father remarried, wedding international icon Barbra Streisand, who became his stepmother. He and his father have remained close across the years.
"I remember when I was 11 my dad took me to the Mission Theater to see Apocalypse Now," he recalls of hanging out with his dad in his youth. "I was probably a bit too young but I remember going, 'Oh my God! What is that, what is that?'
"Again, like that woman at the party, it was a profound cinematic experience. I think it tainted my life forevermore."
Given his father's career, Brolin initially shied away from the idea of acting. "I never wanted to be an actor because my dad was an actor," he says. "I was a numbers guy. I loved maths and all that stuff. Financially, I knew I'd figure out how to make money.
"It wasn't until I was in high school and I did an improvisation class that I thought was amazing. It tapped into all these things that I loved – psychology, sociology, what makes people tick, and how to make an audience member laugh."
His film career kicked off with the 1985 kids' adventure The Goonies, before he then spent a decade, at least, languishing in mediocre films like The Road Killers (1994), The Mod Squad (1999) and Hollow Man (2000). Occasionally, he'd pick a peach, like 1996's Flirting with Disaster from director David O Russell.
His career path changed for the better, however, in the mid-2000s when he was recognised by a string of accomplished filmmakers, such as the Coen brothers and Oliver Stone – who've used him twice – Robert Rodriguez, Paul Haggis, Woody Allen and Gus Van Sant.
He will be seen soon in Rodriguez's long-awaited sequel to Sin City and also in Everest, which is based on the book Into Thin Air by Jon Krakauer.
Continuing his work with august filmmakers, Brolin has just wrapped on a film with Paul Thomas Anderson (Boogie Nights, Magnolia, There Will Be Blood), a dark comedy drama called Inherent Vice, based on the novel of the same name by Thomas Pynchon.
"I just did a movie for P T Anderson that I didn't understand," he says of the experience. "The writing of Thomas Pynchon is so Shakespearean. It was crazy, chaotic but really, really gratifying.
"We took it I think in a direction that the book doesn't necessarily go, hoping it will work." The film represents something of a risk, but Brolin is okay with that; after all, if you don't try, you won't know.
And if the film happens to elicit another interesting reaction from a stranger at a party, well, he's good with that too.