studying is hard initially but after 2-3 weeks you start to notice significant differences in your cognitive function.
Every day you should wake up at the same hour and study until you are tired or are unable to continue. Once this happens, you should do a Warmup Routine (https://www.youtube.com/watch?v=0hhiT6n2-R8&list=PL11x3kZEde6eW0ndsOu1plej6sLFDBpWM&index=5), then some physical exercise (e.g. pushups), and finally finish with yoga. This will relax your mind, allowing you go to go back to studying

DO NOT DO ANY THINGS THAT ARE NOT MENTALLY ENGAGING
GRIND CODEFORCES AND MATH PROBLEMS EVERY DAY
LISTEN TO AUDIOBOOKS/PODCASTS WHENEVER YOU ARE NOT STUDYING
DO NOT LISTEN TO ANY VOCAL MUSIC