Divide your day into multiple study sessions of 1-2 hours max. Then take a break of 15-30 min after every session. The no. of sessions depend upon the situation you're in, like if you have got a lot of syllabus left to be covered, grind hard and increase the number of sessions. Plan your day-to-day objectives, and try to achieve them before end of the day. Write that stuff down on paper, stick it on a wall in your study room or something. The purpose here is to remind you that you must do what is required. No procrastination. PERIOD.
Then reward yourself with some movies, anime, gaming or whatever you like. The satisfaction is real at the end of the day when you know you've done the work.
Now the most important thing is to stay CONSISTENT. It shouldn't be the case that you push yourself crazy hard for one day, and then keep procrastinating on the next one. Pray regularly, exercise, and sleep well.