I think I've told others this on here before, but my top piece of advice for people in your situation is to start doing original work (original research, creative work, etc.). There's no ceiling on that, like there is on most classwork. A lot of the problems that people in your range experience with regard to class difficulty, "potential," "laziness," etc. have to do with the fact that school is an environment with a lot of ceilings on it that you will usually exceed, and that gives you an incorrect idea about what work/effort means. So I recommend finding things that don't have that kind of artificial ceiling so you can learn what putting effort in feels like.
