Nothing Worth having comes easy, so you just have to study study and study some more. Yes, it can be hard and you will be tired and will have to give up (at least partly) partying and some hobbies... but if you want to reach your goal you sometimes have to do that. And do not be affraid or ashamed to ask other`s for help. Studying with a friend or with a tutor (if you can afford one) can be a good idea.