Exam day

I am so nervous now 4 hours before the exam,so worry...I never like this before, how come I am so nervous, Is it because I fail this subject before? or because my prepare is still not enough? I dunno, I just know I am nervous now. Even I try to comfort myself, I still a bit nervous, aiyo, dun care le, keep on study, when i see the question is I know how to do d then everything can be solve