Try to make a schedule that is realistic and try to start with 40mins at a time then 10 mins of break and pre plan your breaks.
A reward system will be great. Reward yourself with maybe your favourite snack for every hour you study or something like that
Try the pomodoro technique
I did this same mistake and Im sufferings lot now , I share my failure story , so that you would do the mistake I did , when I was studying 12th std , I always wanted to take degree which is unique but I ended up taking neet exam but I was never read , even I have taken couching cls , I wasted 27k and I took 1 year drop to prepare for neet but I didn't read at all , I screwed up I wasted 1 laksh this year and I failed this year also , now I'm alone ,all my school mates are in college now , they are studying 2nd year yet I'm failed and not even got any college