How to become motivated (school wise)

I know that high school can really suck when it comes to actually learning and going to class. I had a great experience in high school, due to the relationships I created and the fun I had, but had terrible grades. Let me tell you, if I had not slacked off in school, I could be so much better off than I am now. I still suck at school. I'm in college, and I have the same terrible study habits I had from high school. If you can push yourself to be at least B student in high school, things will be so much easier for you later in life. The work they have you do in high school isn't very hard, and the teachers are more helpful to you. I know it's difficult to see right now, but life gets easier if you work harder. Trust me. The point is, your future will be so much better if you do well in school. Just being able to choose your college alone is a key example. Being able to go anywhere you want is a huge plus. I don't expect you to change from me telling you this, but seriously put your future in perspective, and really think about it.

Senioritis is a known thing, not caring about school because you've already gotten into your universities is pretty standard. As for motivation, you really just have to have a reason to do the schoolwork other than work for the sake of work. If there's something the work costs you(that you care about. Grades are a bit abstract to fill this sometimes) if you don't do it, and do it well, or if the work can get something for you that you want(like university accepatance).