Buddy (Will Blum) grows up thinking he’s an elf — until he gets too big to sit on Santa’s (Ken Clement) lap in “Elf The Musical.” (Amy Boyle Photography)

Will Blum may be the happiest actor to take the D.C. stage this winter. He kind of has to be. Blum stars as Buddy, the titular character in “Elf The Musical,” now at the Kennedy Center.

“Act one is just a gauntlet of Christmas cheer,” Blum says. “It’s the most energy I could expel at one time. But because [Buddy’s] so happy all the time, no matter how I’m feeling before the show, I can’t but help be in a good mood afterwards.”

Based on the 2003 movie starring Will Ferrell, the show is the story of a human who, after hitching a ride to the North Pole as a baby, is raised as one of Santa’s elves. When Buddy discovers he’s a human, he travels to New York to find his biological father.

As in the film, Buddy’s into sugar, smiling and relentless physical comedy.

“I don’t get a lot of chances to leave the stage,” Blum says. “There are even parts of the show where I’m handed secret water bottles and stuff.”

The show’s book, written by Tony Award winners Thomas Meehan and Bob Martin, gives numerous nods to the film and builds out certain scenes for the stage.

“The writers aren’t trying to recreate moments [from the movie], but go beyond them,” says Blum, whose favorite gag adapted from the film involves running through a revolving door.

A fan of the original “Elf,” Blum pays tribute to Ferrell’s now-iconic creation throughout the musical.

“There’s something so wonderful about the way he created this character, so to deny that material would have been foolish,” Blum says. “There’s no point in throwing away the gold in the choices he made in creating this character.”

So Blum will keep smiling, which comes naturally to him.

“I’m very optimistic, and I’m the most gullible person in the world,” Blum says. “So that’s my niche now, being happy.

“It could be a lot worse.”

Kennedy Center, 2700 F St. NW; through Jan. 5, $35-$150; 202-467-4600. (Foggy Bottom)