Hardest thing about College/Uni

I'm starting University in a month, and I know it's going to be a lot to take on. People always say, "School is hard." But they never go deeper into detail. Like, yeah, I get it, but what makes it so hard for you and how hard are we talkin'?

What are some things you wish people would've told you before starting college? What advice do you have for any freshmeat lol. I'm trying to prepare for the long road ahead and to know a little of what to expect. I know some of the issues my pertain only to a certain field or school, but, hell, rant if you need to!