Gus Van Sant was in a reflective mood Wednesday night at the Arclight Hollywood premiere for his dark comedy-drama, “Don’t Worry, He Won’t Get Far on Foot.”

The director noted that it took him over 20 years to get the film made, dating back to the late Robin Williams telling him that he had optioned cartoonist John Callahan’s book of the same title while they were working on 1997s “Good Will Hunting.” Van Sant agreed to come on board because of his admiration for Callahan’s short, “I Think I was an Alcoholic.” He produced two “Don’t Worry” scripts before Williams died in 2014.

“The project kind of got filed into Sony’s system. I forgot about it, so I wasn’t waiting the whole time,” he admitted.

In 2015, a Sony executive reached out to Van Sant about “Don’t Worry,” and Joaquin Phoenix, Jack Black, Jonah Hill and Rooney Mara came on board for key roles. Van Sant shared that he does not make the scenes easy for actors.

“I make them all difficult,” he said. “If they’re not really difficult, I take the time to make something exciting happen, so that makes it more difficult.”

The film follows Callahan, who became an alcoholic at age 13 and was paralyzed following a car accident at the age of 21. He turned to art as a form of therapy, drawing off-color cartoons by clutching a pen between his two hands. He died in 2010 at the age of 59.

Van Sant also kidded composer Danny Elfman, who has scored more than half a dozen of his films, about why he keeps getting hired.

“I just want to keep playing volleyball in his pool,” Van Sant explained. “I want to be part of the team, even though I’m like the worst one.”

Black, who portrays the driver in Callahan’s car accident, recalled actively bragging to friends about getting a part in the film.

“You get the call, and it’s like the Rolls Royce pulls up in your neighborhood,” Black mused. “So at my first meeting with Joaquin, Gus mostly just listened to us. He trusted what we came up with.”

Charles-Marie Anthonioz, Mourad Belkeddar, Steve Golin and Nicolas Lhermitte produced the film. Amazon Studios opens “Don’t Worry, He Won’t Get Far on Foot” on Friday.