I wish that I should've studied hard in high school before entering college. I have chosen a profession that needs a big background into the basics of math. I studied Engineering and I haven't learned anything in high school. If I was just able to exercise my knowledge and spending time reading math books, learning new topics everyday, my engineering career will not be as messy as it is.
I have been struggling even with most fundamental subjects like Algebra and Trigonometry. I find the topics very difficult because I haven't understood any of it when I was in high school. I wish I had that habit before. As a result, I'm living like a hell everytime I went to school.
To the students out there, never underestimate high school. It is a ticket for having a great life when you enter college. Take the topics at heart and you'll surely succeed when you enter the next phase of your life.