JIM Carrey works hard for his money, whether it's spending hours in makeup for The Grinch, or writhing about for his new animated flick from the Dr Seuss storybook.

JIM Carrey is switching things up.

The actor, who earned a record-breaking $21.3 million for his role as The Cable Guy is now making his animated debut in the film version of the classic Dr Seuss book Horton Hears a Who!

Carrey is the voice of title character Horton, an elephant who discovers the entire city of Whoville on a nearby speck of dust and makes a promise to its mayor (voiced by Steve Carell) to carry the city to a safe place.

This is easier said than done, because only Horton can hear the Whos -- meaning he must overcome a jungle full of doubters to accomplish his quest.

Much like his animated counterpart, Carrey found his seemingly easy job (voice-work) much harder than expected.

‘‘I was surprised at how physical I had to be to create the different scenes,'' he says, reclining on a couch at an upmarket Beverly Hills hotel.

‘‘I went home raunched out and sore from head to foot. I thought ‘What the heck? Am I doing an action movie or something?' But you have to put yourself through it.''

Carrey's in-studio antics proved beneficial -- they served as a guide for animating the Horton version of the actor.

‘‘They had a little video camera there the whole time,'' he says. ‘‘And (co-director) Steve Martino was sitting there with a sketch pad, which was so cool because he's an amazing artist.

‘‘He was turning whatever I was doing right at that moment into Horton while he's sitting there doing these sketches.''

Carrey credits his tenacity partially to his Canadian heritage and says he sees the same trait in many Australians.

‘‘All the Australians I know are really cool people,'' the lanky 46-year-old says. ‘‘They remind me a lot of Canadians -- they have the same kind of vibe, the fun-loving, cool vibe.

‘‘Certainly a lot of amazing talent is coming out of there -- Jesus, it's incredible. I think it comes from a desire to do something extraordinary. I think you try harder when you come from a place like that, you try harder to be good.''