[danielf]

Firstly, I would say that it is important to not cram your revision into a small time period. Rather than revising 12 hours in one day, start early, and do three days with 4 hours each. Make a summary of what you've revised to go over when the exam comes near.

As for getting yourself to revise. As with the above, get into a routine. You may want to consider revising somewhere else than at home (e.g library). Just get yourself to do a set number of hours everyday. If it helps, make it the same time slot every day. Boring, I know, but the trick really is to make it into a routine.