(CBS NEWS) – John Goodman’s new movie is a monster hit. Disney/Pixar’s “Monsters University” made $82 million at the box office this weekend — one of best openings for an animated film ever.

Goodman is the voice behind the teal and purple monster Sully.

Playing the monster is an exhausting endeavor, according to Goodman, who said his four-hour taping sessions tired him out. “You have to put everything in your body into it,” he said on “CBS This Morning.” “The skill for my end, the only thing I can talk about, in order to make the creatures breathe…you throw your whole body into it and everything you have. Over and over and over and over again. I mean, they’re satisfied, but they want alternate takes.”

Goodman said he doesn’t visualize the character — he tries to become him. “It’s odd,” he said. “(It’s) one of those things that sounds terrifically boring to everybody else. But it’s fascinating to me.”

Goodman is opposite Billy Crystal in “Monster’s University.” The actor has shared the screen with a number of other “A-list” stars, from Denzel Washington to, most recently, George Clooney for the film “Monuments of Men.”

Goodman and Clooney weren’t strangers, though. They knew each other from the hit series “Roseanne.” Clooney played a supporting character while Goodman, who played Dan Conner, was in a starring role.

Goodman joked of Clooney leaving “Roseanne,” “He had the good taste to quit the show. And his career suffered ever since.”

“(George) is childlike, not childish,” Goodman said. “He’s got so much energy and creative flow and goodwill that permeates from the top down.”

For more with Goodman on his roles and his upcoming projects, as well as his memories of James Gandolfini who recently died at the age of 51, watch the video above.

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