Right before an exam I feel absolutely amazing. I study as much as I can the previous day, sometimes even burn the midnight oil, but at the exam I am as cool as a cat. I don't know why, maybe its because I feel that there is no point worrying now. Also I feel that if I stress out, I may forget stuff, so I just stay cool and write stuff. Yep, sometimes, even when I don;t know the answer, I just write stuff, it reduces stress for the rest of the exam.