When it comes to making an Adam Sandler movie, humor is hard work. It’s a juggling act of joy and fear.

That comedic credo comes from longtime Hollywood director Dennis Dugan, one of the veteran actor’s favorite directors and the guy whose job it is to figure out what’s going on inside Sandler’s mind.

"If you don’t have the jitters when you walk on the set every day, you’re dead," he said. "It’s fun and scary and challenging."

Well, something must be working. Dugan and Sandler have been making movies longer than a lot of Hollywood marriages — 15 years — and their latest release, "Just Go With It," will light up screens today with scenes of Hawaii.

"What keeps me coming back is we love each other, we love comedy," Dugan said in a phone interview from New York as he prepared for a premiere of the pair’s sixth collaboration. "What I like about Adam is he is constantly trying new things, constantly challenging all of us to do better and be original and be as funny as we possibly can."

"Just Go With It," which was filmed last spring on Maui and Kauai, stars Sandler as a plastic surgeon who pretends to be married so he can score with the ladies. The Happy Madison production from Columbia Pictures also stars Jennifer Aniston, Nick Swardson, Brooklyn Decker and Nicole Kidman.

The 64-year-old Dugan, whose films with Sandler have brought in more than $800 million, calls his their partnership "a dream come true." Their work on "Just Go With It" was typical. Sandler has created a writing and production team that he uses for all his projects, which means everyone is familiar with each other’s creative ideas and mood swings, Dugan said.

"We have all worked together for so long that we don’t have an ego about who comes up with the joke," he said. "We’re just sitting there trying every day to make the film as funny as possible."

Sandler and crew do not make films like their Hollywood peers, Dugan said. When they shot "Just Go With it," he told Aniston that she was going to get direction from all corners, including Dugan, Sandler and the writers on set.

"It is a different atmosphere than most movies," Dugan said. "There is nothing we leave to chance. There is no detail that is too small to hammer on."

But their 200-member production crew makes a big footprint, and that meant the location filming in Hawaii needed extra care, Dugan said.

"Just Go With It" required a resort hotel setting, and the search for the right one took three months and many overnight stays. Dugan and his production designer started their hotel tour on Oahu, then flew to the Big Island, but nothing seemed right.

Their last stop was Maui and the Grand Wailea, with its large swimming pools and photogenic beach, lobby and luau. Perfect.

"We were able to go there and not impact anyone’s vacation in a negative way," Dugan said. "That was something we had to think of. Adam loves the Kahala Mandarin, he always stays there, but there is no way we could go in there and take over the one swimming pool."

After four weeks on Maui, the whole crew moved to Kauai to film a waterfall in a jungle setting that turned out to not have enough foliage — so they brought more.

Dugan has been directing since 1987, when he helmed two episodes of NBC’s "Hunter" with Fred Dryer — but got his start in 1971 as an actor. He appeared in a wide range of shows: "The Mod Squad," "The Rockford Files," "Hill Street Blues" and "Moonlighting."

In addition to the six Sandler-Dugan films, the director just wrapped up the comedian’s "Jack and Jill," which also stars Oscar-winner Al Pacino.

A longtime photographer, Dugan bought his first film camera with money he won in a poker game. He discovered as he filmed personal projects that it suited him better than standing in front of the cameras.

"It just sort of fits my brain better," he said.

The same is true of comedy, even though he directed six episodes of the ABC cop drama "NYPD Blue."

"I haven’t ever really pursued anything else and I doubt I would get hired for anything else," he said. "I am OK with that. I want to do the one thing and do it well. I’m not going to spend my life trying to make my statement movie. Nobody wants to see it."

But there’s no secret formula for making funny films, Dugan said.

There has to be a dynamite script. Then you hire talented actors and turn them loose. That’s what happened when he directed "Just Go With It," he said.

Kidman surprised him with how funny she was and Aniston smacked back every ad-libbed line from Sandler like the comedy pro she is, Dugan said.

And the script will make people laugh.

"I think, honestly, it is a really funny movie and it is a really romantic movie," he said. "If you take your wife or your girlfriend — or you take them both — they will be happy you took them. And you will be happy you went."