The actor plays a former military captain who is transported to Mars in the sci-fi epic and he took on a strict regime to get him in shape for the role - but the lifestyle overhaul was a struggle.
He tells the Associated Press, "It's the most boring diet you could think of, really, it was four months before (filming) and seven months during, so an 11-month regimen with that.
"Training at 4.30 in the morning before you go to work, and then training for the four months before as well. And then during the day, you're training as well before takes.
"I'd say the emotion is probably the toughest thing especially, it's quite heavy some of the stuff he goes through."