SYDNEY, Australia—If there is one thing Ben Stiller is aware of, it’s that he is living his dream.

Having just walked the red carpet, Stiller is now speaking to the press and guests at the premiere of his new film, “The Secret Life of Walter Mitty,” at the Sydney Entertainment Centre.

“Directing different kinds of movies, I love doing that, for me that’s my dream as I grew up wanting to do as a kid,” he says. “You talk about daydreaming, when you’re making a movie, that’s basically what you’re paid to do. You’re just thinking about this thing in your head all the time, that you’re trying to get down into reality somehow. So, I feel very fortunate that I get to do that all the time.”

That’s ironic, considering the origins of this movie. “The Secret Life of Walter Mitty” is based on a 1939 short story by James Thurber about a middle-aged, married man who keeps escaping his real life for fantastical adventures in his head. It has even entered the American vernacular, where being “a Walter Mitty” or “Mittyesque” is to just daydream all the time and let life’s opportunities pass you by.

Stiller made sure, however, this chance didn’t pass him by.

Like many Americans, he discovered the short story in high school. But it was already as a successful actor and director that he regained interest in it, when he encountered the “Mitty” script by screenwriter Steve Conrad (who also wrote 2006’s “The Pursuit of Happyness”).

Unlike the 1947 Danny Kaye film adaptation, Conrad’s script was a serious departure, taking only one aspect of the story and running with it in a completely different direction. Instead of escaping his life’s challenges, Mitty now faces and embraces them.

“He’s in a box, he’s a guy who’s sort of constrained by the responsibilities of his life and the world he’s living in and the life that he’s lived. And we all feel we can relate to it, where you just get bogged down with everyday life. And you have these great dreams and this potential but we have to get through life every day,” says Stiller.

The script convinced Stiller to get the film done, and that’s exactly what he’s done. The Mitty on screen still retreats occasionally into daydreams until radical changes in his life force him to confront reality.

Life Magazine

Conrad wrote “Mitty” when he was a negative assets manager in Life Magazine—just as the publication is taken over and brought online, resulting in layoffs and other challenges, something that happened in real life.

“It was his idea to put the story in the context of Life Magazine going away and sort of this transition that we’re in, in our world, from an analog world to a digital world, that I feel that I can connect with generationally having lived through the totally predigital world and just watching it all change,” explains Stiller.

This led to Mitty having to go to far-off places to find a missing negative from reclusive photographer Sean O’Connell (Sean Penn) to use as the cover of Life’s last printed issue.

It’s a quest that changes Mitty’s life.

Among Conrad’s other additions is Cheryl, a colleague that Mitty pines for. For this role, Stiller cast “Saturday Night Live” alumna Kristen Wiig, best known for writing and starring in “Bridesmaids.”

Wiig joined Stiller in answering questions about the film. “She’s an amazing actress and a brilliant comedian,” Stiller says of Wiig. “But what I’ve always seen in her work is this just very real, rooted, grounded reality …”

Wiig digs the film’s message: “I think it reminds us to connect with people in an age where we are so connected with our phones and things like that. And it makes people want to travel and go after their dreams if that sounds cliché, I don’t know.”

Outstanding soundtrack

One important aspect of “Mitty” is how Stiller himself chose the film’s outstanding soundtrack, featuring memorable tracks from Of Monsters and Men (just try getting “Dirty Paws” out of your head), Arcade Fire and, in particular, the pairing of Argentine singer Jose Gonzalez and composer Theodore “Teddy” Shapiro.

“When you’re directing a movie, that’s all the stuff you do,” Stiller says, adding that they played a lot of music on the set.

Making “Mitty” brought many challenges, including shooting a particularly intimate scene on 6th Avenue in New York. “‘Zoolander’! people were shouting,” Wiig recalls. “Or  ‘Focker,’ yo, ‘Focker’!’” Stiller adds. “It’s like, ‘I’m trying to act man, I’m not ‘Focker’!’”

A windstorm struck the film’s location shoot in Iceland, shutting down the set just as the production team was working on scenes with Penn. “A squall would come and then the sun would come out and then it would rain,” recalls Stiller.

Stiller has surrounded himself with an impressive cast. Aside from Wiig and Penn (“one of my favorite actors”), there’s Shirley MacLaine, Patton Oswalt and Adam Scott.

“Mitty” is many things at once: an ode to print and still photography; a sweet workplace romance; an adventure around the world.

Though it has humorous moments, perhaps the film’s most surprising element is it’s not a comedy like Stiller’s wildly popular 2001 film “Zoolander” and 2008’s “Tropic Thunder.” It’s actually a richly layered mix of different genres, which is exactly what Stiller wanted.

“It didn’t fall into one category but I just connected with it,” he says. “And I guess I could connect with it on a personal level. But I love movies that you can’t really categorize by genre.”

20th Century Fox’s “The Secret Life of Walter Mitty” opens in theaters on Jan. 22, 2014.