My biggest fear is overreaching. I have been in situations where I felt swamped, and it's turned out really well; and I've had other situations where I've had to walk off the film after five minutes because I realized I was in way over my head.
I'm always curious about how actors cry on film.
I was thrust into a really lofty, enviable, but isolated position with 'Princess Diaries' in that I could carry a film before I really knew if I could act.