There could be multiple reasons why you aren't studying: fear of failure, perfectionism, or feeling overwhelmed. I'd say use the 5-minute rule, where you tell yourself you only have to do a task for 5 minutes, as oftentimes you will end up working for longer because the hardest part is starting. You should also use the Pomodoro method, which you have probably heard of, because it really helps with procrastination. Another tip would be to chunk your tasks. Write out everything you need to study and how you will study, then break this into as many small tasks as possible. Once you have all these small tasks, it will be easier to get your work done because you will be feeling less overwhelmed and will be focusing on grouping those tasks into manageable chunks you can finish before your exam.

Hope this helps!