Ben Stiller spoke candidly about the process of making The Secret Life of Walter Mitty at an advance screening of the film on December 7 in New York City, which also celebrated his work as a director.

The Lincoln Film Society hosted Ben Stiller Directs, a retrospective of the actor's work -- featuring films like Reality BitesTropic Thunder, and Zoolander -- from Dec. 6-8. Enstars was present at the event where the filmmaker discussed the inspiration behind Walter Mitty, the detours he took from the original short story, deleted scenes and having to get out of his comfort zone as a director.

The film, which is based on the 1939 short story by James Thurber, takes viewers inside the expansive and wildly imaginative mind of Walter Mitty (Stiller). The lead character is prone to day dreaming as a form of escaping his dreary existence as a Life magazine employee responsible for developing and archiving photo negatives for the publication.

While the escape in Thurber's story was restricted to day dreams, Stiller's character actually starts to live the fantastical in his pursuit of an elusive photographer (Sean Penn). Stiller talked about these differences as well as his relationship to the book and original film adaptation that came out in 1947. 

"I read the story in school and always remembered it, remembered it because it had a very complicated language the character spoke," he said, adding that he was probably nine years old at the time.

The story stuck with Stiller over the years, as did the iconic character who was a day dreamer. What actually got him thinking about developing the film was when he read a different version of the story through a script he got nine years ago. Reading Steve Conrad's draft made Stiller feel very engaged with the story. Conrad's vision also sought out "paying a homage to regular guys."

"I think he took this idea, which I guess was in the original movie, a real thing happening to Walter, but in his screenplay it was all him trying to go out into the world to find this negative and it is really about him getting in touch with himself as opposed to getting involved in some real life caper that I think in the original movie was just a much broader, kind of musical comedy," he said. "I think it was just a different goal for this film."

Stiller cited films including The ApartmentThe Graduate, and Being There as inspirations for the film. He put emphasis on Hal Ashby's genre-defying style of filmmaking, which he wanted to emulate with Walter Mitty. The director compared Mitty to the protagonist of What Makes Sammy Run? and the transcendent quality of the character.

"That's an iconic character that Budd Schulberg wrote in his novel a long time ago, writing about this guy who wants to get to the top and who will do anything to get to the top," he said. "Though that movie was never made, it got rewritten and done in different ways."

"I feel like Walter Mitty is the same type of character where this character becomes a part of our culture even though there was a Walter Mitty movie but the character becomes bigger than the actual movie or story than it as presented in," he added.

While speaking about editing the film, which Stiller believes "set the tone" for the entire project, he talked about deleting a few "fantasies" that felt too "sketch-y." By way of example he cited a scene where Walter walks over to Kristen Wiig's character in Central Park, which seemed like a sketch out of Downtown Abbey.

"It was sort of a Downtown Abbey-esque kind of a scene where she is the lady in the house and I am the man servant, it was funny and we shot it and immediately when I saw it I felt this was too much of a sketch or something," he said.

Despite all the bleak circumstances Stiller's harrowed character emerges from, The Secret Life of Walter Mitty is a tale in optimism and hope. It ends on a happy note where things seem to start falling in place for the protagonist. Stiller spoke about the novelty of working on something like this and betraying his more critical view of life, which has often been reflected in his past work.

"While making this film I realized it was less cynical, it was uncharted territory for me as a director," he said. "Some people who have watched the film talk to me and tell me that they feel it is very 'heartfelt' or they feel it's 'feel-good' and I go ooh, that is not what I meant," he said. "I knew that it had a 'happy' ending but for me it was never what I was aiming for other than telling the story and following this character. I did want people to feel something and I definitely didn't want it to be cynical. I guess I realized that later in the process that this is something new, something I haven't explored before."

The Secret Life of Walter Mitty hits theaters Dec. 25.

Watch a trailer for the film here: