“It’s a workout, I tell you. It’s something—back-to-back-to-back. It’s been a full day.” Rainn Wilson, best known for playing Dwight Schrute on “The Office,” might have been talking about filming a season’s worth of episodes of the show, or his demanding debut as a leading man in “The Rocker.” But he was actually referring to his interview schedule in Dallas, which extended from early-morning radio and television appearances to a late afternoon round table, with time out for phoners to other cities.

But Wilson, who’d visited the city fourteen years ago for a run of “Room Service” at the Dallas Theatre Center, still happily talked about his role as Robert “Fish” Fishman, a drummer bounced from his heavy metal band Vesuvius in 1986 who, two decades later, sits in for an impromptu gig at the prom with his nephew’s band and, as a result of his habit of practicing naked via webcam, makes them unexpected stars on YouTube, winning them a record contract in the process. The idea behind the story appealed to him: “What would it be like to be cut from a band before they’re huge? And what if you got a second chance at fame, at living the dream?”

But it was not a role that came naturally to Wilson.

“I was a bassoonist in high school,” he admitted. “I was a band geek, among all the different types of geeks I was in high school. Also a model United Nations geek. And on the chess team—I competed in chess, and” (channeling Dwight) “I can beat any of you, or all of you put together. I was not a drummer.” Nor was he a heavy-metal fan. “I grew up listening to classic rock,” he said. “And later I was more into punk and new wave.”

But when the project came together, Wilson started to become Fish. “As soon as the movie got green-lit,” he said, “a set of drums showed up in my garage, and a drum coach showed up, and we started working out. And it really is a workout. It’s exhausting.

“And I did a lot of research on heavy-metal drummers, got a lot of YouTube videos from the era, from back in the day. That helped me find the character, because drummers are kind of like idiots. They’re not cerebral types—they’re their own breed. That created Fish, whom you see before you—the drummer as showman, the ringmasters who got lowered onto their drum sets and had spinning drum stools and flashing lights and pyrotechnics, and stuff like that. That didn’t really start before heavy-metal drummers.”

And Wilson got a charge out of doing the musical numbers. “It was cool,” he said, “because I really got to live the rock-and-roll life. We got to have hundreds of extras and a big sound system and light show, and run on stage and get cheered and play through a bunch of songs, and have people screaming. You know they’re all being paid to do it—it was totally artificial. But it was really fun to get a little taste of it. There’s a lot of adrenaline out there.”

Of course, it might have been a tad embarrassing for some actors to do the “Naked Drummer” scenes, but they didn’t bother Wilson.

“Vanity is not in my vocabulary,” he said. “I have no shame exposing my big, weird, pale, flabby body for comedy. It’s been getting laughs for a long, long time, and hopefully will be getting many more.

“I had an agent very early on in my career who called me into her office and said, ‘I just think you need to get your teeth fixed and get tan and work out and build up your shoulders.’ And something didn’t sit right with me with that. I’m never going to be that guy, just never. Even if I totally bulked up, I would just be like a weird bulked-up guy. It’s just not me.”

But Dwight Schrute and “Fish” Fishman are.