1) It may be that I studied too hard, lacked exercise, and my physique became worse when I was in Grade One and Grade Two. I feel powerless.
2) Some of the things I have learned before are unfamiliar, or have a fixed mindset, so the original method is not suitable for new questions;
3) Do you have anything that has been bothering you and making you unable to concentrate on your studies?
I suggest that you have a regular schedule and plan what to do on this day, especially this time, so that you will be efficient and energetic to study;
Fully understand the definition, don't memorize it by rote, and use it flexibly, especially in mathematics. There are too many questions, so you can do a problem, know how to do it, know why you did it, and filter your thoughts.
At this time, students are more agitated and should be tolerant of things. There are many unpleasant things that can be avoided. Don't let them interfere with your study.
Finally, I wish you an early adjustment and admission to an ideal university.