bhai just think that it's the easiest exam of life and u will get best marks in this among all exams u have given in ur life. just keep on focussing at ur goal. just make down a cardboard and there write that why u want to be a doctor .....write the reason according to ur mind... and believe me that would be enough to tell u about ur changing future.
2nd self believe .....which is must, because self believe is a fuel of subconcious mind, and harmony between ur dreams and future is hidden in self believe and self motivated talk....always reminds urself about you..and ur reality and at last i want yo say that u r the best if u r doing hardwork then no one is able to stop u.