Achieving the impossible

A bit late but welcome to Nofap, where dreams are made one step at a time.

If this entrance exam is very important, the most important habit to build is probably studying. Habits are basically trigger -> action -> reward. It's kind of like programming to your brain. So have some trigger (could be a object in the room) that tells you that you need to study, do it for at least 25 minutes and finally give yourself a reward (typically gratitude as we don't want to cheat the system).

Otherwise, read the wiki at r/getdisciplined (at reddit). It should be to the right of the main homepage. There, follow their instructions and choose a method. This method you record with a tally counter (either on your phone or physically) for every time you follow it successfully.

That's all. Have a great day.