Gerard Butler's new role Machine Gun Preacher was one of the most difficult of his career.
The actor takes on the role of Sam Childers in the Marc Foster directed movie who is a former drug addict who finds God and became a crusader for hundreds of Sudanese children.
And the actor admits that it was a very emotional and difficult role but, in the end, one that was very rewarding.
Speaking to the press Association the actor said: "I really had to take myself to places that I had never been before.
"It's the film that I've been most involved in as well. It's just been a marathon. Every day was epic.
"I'm sitting with my folders of visual aids, images from Sudan of kids burned, people hacked up, babies... Sometimes I would think, I can't do this again.
"It was a hard movie to make, but it's the hard ones that pay off big."
Machine Gun Preacher is the first role for Butler since The Bounty Hunter but the actor has plenty in the pipeline including Coriolanus, which is the directorial debut of Ralph Fiennes.
He has also completed work on Playing the Field and Movie 43, which also stars Emma Stone, Kate Winslet and Hugh Jackman.
Machine Gun Preacher is released 4th November.
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