In an interview with The Daily Star, for the DVD launch of The Last Witch Hunter, Diesel says he was banned from going to the gym by his director, so that he could look more like he’d been born back in the 13th century.
I haven’t come across that in a long time. They said that I could look strong, but I could look a little bit more everyman too. I think some directors just want me to go against type – it’s how they want to play with my characters.
He also says his lifelong love of Dungeons & Dragons helped him in the role:
I’m a huge fan of Dungeons And Dragons and I even wrote the foreward for its 30th anniversary book. It’s something that was a big part of my life and it’s probably affected the way I approach making and producing movies. It played a huge part in this film; I haven’t done anything in the fantasy genre before…Well, I was raised by a mother who was an astrologer. And I believe you have to be receptive to all kinds of things and that includes the supernatural. I believe that my love of fantasy and Dungeons And Dragons allows me to be open-minded.