In high school I got away with never having to do any homework. When I got to college I assumed the same could happen. I was mistaken. I would tell myself that college is difficult and you need to go above and beyond with your work inorder to succeed. I also would say that college is the most important time of your life and that i needed to take it very seriously. In the real world all jobs want to know is what degree you have or where you went to school so in order to be succesful you need to focus in college and not party as much.
Prepare earlier and do your best in school but avoid stressing out by doing things that make you happy.