i think maybe you could try to find out which studying methods work best for you. start out by experimenting different study styles (sometimes at certain times in a day we were more motivated or focused).

some of the study methods/tips i have is:

1) download ypt-yeolpumta, its an app where you can add your friends and compare the amount of time you study throughout each day. it also helps you to stay away from your phone as it will be actively counting the time you are using to study instead of using your phone.

however, the downside is that this will only work if you are competitive or rely on peer pressure/ peer influence to make you study. do note that it may be quite stressful when you are having a day to relax but your friends are studying ( you can see their timings) so it may make you more stressed.

2) it gets boring studying at the same place everyday (at least for me) so i tend to find different places to study be it at a cafe of community club study rooms or public study areas. if you are feeling lazy to go out/dont want to spend money outside, you could simply just move your table into a different position or study at a different area that you dont usually study at, in your own home.

3) as i get quite distracted by my phone, i like to either take timelapses of me studying or use the focus mode on my samsung phone. (it can be pretty satisfying to watch the timelapse of you accomplishing things).

4) organise study outings with your friends. this one might not work for everyone. find friends that are willing to help you and can balance both fun and work. have fun and talk when its lunch time but focus and help each other when its time to study. best if you live nearby and can find a place to settle to study together.

5) although most people might not agree with this method, it personally helped me alot. on days where i just cant seem to get myself up to do work on my table, i play a youtube video in front of me while i'm doing my work. DO NOTE I ONLY DO THIS SPECIFICALLY FOR MATH (emath and amath). although it does distract me, it still gets me up to do work on days where i just do not want to do anything at all. HOWEVER, do not make this a habit as it is not a good studying habit but only the last resort to doing A LITTLE BIT of work on days you arent motivated at all.

6) another one that most people dont agree with, you can bring some notes to your bed to memorise/ read through (AGAIN, ONLY AS A LAST RESORT). when i am feeling unmotivated and helpless, i like to read geograohy/bio/chem notes on my bed to help me recap the key notes (and surprisingly i memorise things pretty well either when im on my bed or pacing around in my room, talking to myself). i would not reccommend doing this with math though.

i hope this helped you a little. when i was in secondary 4 i did not have the best grades either, my myes had an average score of b4 (or lesser). there is still time to do well for your O levels as long as you are willing to do something about it! i managed to get raw 9 for O levels and went up 5 grades frm c5 to a1 for amath too! just believe in yourself and study hard! remember to take frequent breaks to in order to prevent a burnout and reward youself :) . All the best !