Henry Cavill says preparation for 'Superman: Man of Steel' has been "really hard stuff".

The British actor revealed he is a month into a gruelling training program to get in shape for his role as Clark Kent and his superhero alter-ego - and more is yet to come.

He said: "At this early stage it's just doing some foundation training. The guys from Gym Jones, Mark Dwight is training me. I've done about a month so far of foundation training. Really hard stuff, to get my body used to the real stuff, which is coming up soon.

"So at the moment it's just getting my body in the right aesthetic shape."

Although the 'Tudors' star says his character will have an other-worldly body, he insists his Superman will have a large human element, so audiences can relate to him.

He continued: "I think it's a great way to go, because superheroes themselves are so unrealistic that to add a realism to them just makes them easier to associate with and attaches more directly to a real life imagination."

The new film will be directed by Zack Snyder and is due for release in December 2012.