The star tackles light action scenes in the Twilight vampire franchise and she was sure that was enough experience to prepare her for the battles she would fight in the dark adaptation of the classic fairytale.
But Stewart was left licking her wounds when she actually stepped onset with her co-stars Chris Hemsworth and Charlize Theron - and she ended up hurting her hand and injuring her foot when certain stunts went wrong.
She tells MTV.com, "It's funny too because I became such a baby on the movie. I was scared of so much that I didn't think that I was going to be.
"I tasted little bits of action in other movies, and I thought that I was such a huge bada**. I was like, 'I love it. Honestly, I just love how it (doing an action scene) makes you feel. It feels real. You get to actually do it, and then at the end, you're not like I faked it.' I faked a lot. It was hard. I hurt myself, but it was fun."