The US actor best known for comedies like Meet the Fockers and There’s Something About Mary, and the hit Night at the Museum action franchise, said he enjoyed the change from more familiar fare.
“For me it was an opportunity to work with (director) Noah (Baumbach), who I was a big fan of,” Stiller told reporters after a press screening at the Berlin film festival, where Greenberg is in the main competition lineup.
“It was great to be able to work in a movie that was not that other kind of film,” the 44-year-old added.
Stiller plays Roger Greenberg, a 40-year-old part-time New York carpenter recovering from a mental breakdown who travels to house-sit for his wealthy brother at his home high in the Hollywood Hills.
Determined to do nothing, and not feel guilty about it in bustling Los Angeles, he reunites with two old band mates who are still bitter at his decision 15 years earlier to reject an offer from a major record label.
He falls for his brother’s assistant Florence, played by Greta Gerwig, but mental issues and an awareness of his own shortcomings make him unpredictable and abusive.
“I think it’s a really believable path that these people are on,” Stiller said of Greenberg and Florence.
Welsh actor Rhys Ifans plays Ivan, one of the band members who is overcoming a drink problem and has a son whom a self-centred Greenberg never bothered to get to know.
Ivan tells a shocked Greenberg how others perceive him, and the two reflect on life with the bitterness of people who feel they could have done more.
“They say youth is wasted on the young,” Ivan says.
“Life is wasted on people,” Greenberg retorts.
Further comedy comes from the protagonist’s obsession with writing letters to corporations and city officials to complain about whatever bothers him, accusing Starbucks of serving lousy coffee and American Airlines of having faulty seats.
As well as a love story, Greenberg is a movie about growing up.
“Life sort of creeps up on you,” said Stiller. “I’ve got two kids, and kids force you to thinking outside of yourself a little bit.
“There is a feeling like you have … your life ahead of you. Greenberg is really coming up against the fact that he doesn’t. You have to accept those things and that’s part of growing up.”
Baumbach wrote the script with his wife Jennifer Jason Leigh, who also appears in the movie.
The New Yorker is best known for his scripts, and was a writer on Wes Anderson’s The Life Aquatic with Steve Zissou and Fantastic Mr Fox.