“I was in the wilderness, and I probably should have left a trail of breadcrumbs, but you found me,” the actor said to director Darren Aronofsky.
The Gavin & Stacey actor felt he was "too young to do it justice".
Darren Aronofsky has hit back at critics of his new film, which stars Brendan Fraser in the lead role.
"It’s an impossible role to fill with a real person dealing with those issues."