When I really need to get something done but find myself resisting, unable to focus or indulging too easily in distractions then I use a technique that I created called "Negative Affirmations"
This works in harmony with our survival instincts. It first requires you to think about the bad things that will happen by not taking action and then immediately gets you to focus on the positive action that will take you away from the perceived danger. It primes the mind by taking account of powerful survival instincts and harnesses that power highly effectively.
It's a lot quicker and easier than meditation. You can read all about it here
Negative Affirmations
(Sorry if it's come too late to help you with your exam this time around!)
Take care,
Nick