Charlie Hunnam spent 14 hours a day, for 27 days, on a cross-trainer while filming 'Pacific Rim'.
The 33-year-old actor - who plays pilot Raleigh Becket in Guillermo del Toro's sci-fi blockbuster - had to muster all his strength while on set as some scenes required him to use the exercise machine for hours at a time.
He told the Metro newspaper: "There are a bunch of sequences where I pilot the giant robots. They created what was essentially a cross-trainer for us to operate them. It's hard enough to do that for 30 minutes at a time, but I did it 14 hours a day, for 27 days, wearing a 30lb suit. There were moments I thought I wouldn't get through it but it was worth it in the end."
Hunnam is set to join del Toro in another film, 'Crimson Peak', after the pair decided they made a great team and enjoyed working together.
He added: "Guillermo and I had a wonderful time working on 'Pacific Rim' and at the end of the movie he said he'd like to work with me again.
"The feeling was mutual and I was very touched to hear that. He called me three months later and said, 'Hi amigo, I have found us another movie to do together.' "
'Pacific Rim' will be released on Friday (12.07.13).
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