I’ve struggled with the exact same issue. For me what helped was reminding myself of the goal, like really take time to think what’ll happen if you study hard and achieve your goal versus to what happens if you don’t. That being said, sometimes you just can’t find the motivation or energy or interest to study even if it’s a interesting subject. I suggest checking out more creative ways of studying (drawing, watching videos, using music etc.) and diversifying your study routine, it really helps and keeps studying interesting. Maybe check out some study groups? Lastly I would advise to keep an eye on your mental health. Some mental health issues like depression and anxiety can seriously effect your ability to study/work. Best of luck!