BAD, Bad, grades

I do have some grades bellow a 50, and a few zeros. What i do is procrastinate, or not do my work at all. Recently, i compared my self with what i was in elementary. And truth is, i dont like it. Before, i was always on top, and an 80 was a bad grade. Now, i see a 70, and i think, thats good enough, but i know better, and so does my elementary persona. So from now on, i will do my best to get 80 or more, and if i can, 90s. That way, i can achieve my goal of being top 10 in my class, (since 10th place is like 2 or 3 points away), and have a gpa of 3 or more.