It also gives a boost of energy that is especially needed during the exams. You cannot realize how valuable and important exercise is until you have done it for some time. I know it sounds ridiculous, but instead of cramming 12 hours a day for five days during the finals, spend one hour each day at the gym. I bet you will immediately feel the difference. You will not lose that hour because you will in fact be studying more productively the other 11 hours.
Time management is at the roots of success.
You need to choose a setting where you study best. I found from experience that oftentimes the worst way to study is in a group or in proximity to people. You end up talking a lot, answering questions from people who have not done the work and working on areas that are not your weakness. It is a waste of time. Out of two hours of study you may only get 15 minutes of productive information going to your brain.