I want to do well but I'm not trying hard enough (year 13)

I really want to do well but I feel like I'm not trying hard enough. I feel tired all the time so it's difficult for me to actually try hard and be consistent with my studies. I really want to do a course that required ABB but my predicted grades are currently CCC and all my tests aren't proving that I can get at least BBB. I'm just tired of all this

It'd be a hard slog to go from CCC to ABB in the time from now until exams but not impossible. If you're tired maybe try doing more exercise, changing your sleep schedule, your diet, there's plenty that can be done. Good luck