Yes what are good exercises to do when studying for an exam?

Mediation for 2 minutes
Drinking cold water or coffee
Seat in a blue room or on a comfy place
Apply on your above eyes this prevent you to sleep

Practise books of that specific subject, rereading your notes from class, and color quoting(from your notes or a book you color for example blue for the important, yellow for the things to keep in mind etc.