Robert stars opposite Willem Dafoe in Robert Eggers' new thriller, but had to go to extreme measures before filming as he doesn't feel like a good enough actor without putting himself through hell.
Revealing he would punch himself in the face, twirl around to create dizziness, or drink mud he told The Observer, "Because I don't really know how to act, I kind of wanted to somehow make it real, and one of the ways I've always thought makes that a little bit easier is if you shake up your physical state just before action. You end up walking into a scene having a different feeling."
However, as he was wearing a mic the whole time, the star admits his antics might have put off his castmates.
"I forgot I had a mic on the whole time, so the producers and the director, before every single take of the movie, would get...(performs retching sound)," he informed the British newspaper. "It kind of puts everyone else off."
Robert became a superstar after playing Edward Cullen in the "Twilight" series, and said international fame got to him - but doesn't now he appears in smaller productions.
"I think the stuff about fame is the most boring," he explained. "There's nothing to say. Literally think about what you imagine fame to be for one second. It's like that! People recognise your face. That's it."
"When I was younger, when I was a little bit more insecure, I kept thinking people were disappointed when they met me. Now I don't give a s**t."