What do you wish you had known (at any point in your education)?

So, I'm always looking for a place to learn new things that may help me out with school (or jobs, or life, or friends, or pretty much anything), so this question is simple: what do you wish you had known?

Originally, I was thinking "What do you wish you had known when you started engineering school?" but I realized there's a ton of situations besides (and including!) first year that most engineering students could probably use a heads up on.

For me: (Starting school):

• I was told throughout high school, consistently: "XYZ subject is really hard. You're going to struggle, and it's going to suck." I never struggled with any of the subjects they said I would. Thus, when I entered engineering, I couldn't help but wonder, "Are they just crying wolf again?" They're not. It's hard. And it sucks sometimes. But the rest of the time, it's so amazing and awesome and inspiring that it makes the sucky times worth it.

• You can get by without being really good friends with anyone in your class. I did for years, just because I'm painfully shy and the first couple years at my school have huge classes. It's just easier not to.

• There will almost always be something on an exam that you didn't study. Just move on and don't let it freak you out.

• Try to take something out of everything that happens to you. Failing a class isn't the end of the world, as long as you learn something (about yourself, about studying, about time management, whatever ... even if you learn a third of the material in the course). Also, I know you probably have to take some arts courses, so at least learn something and make it worth your time.

• You can study an hour for a midterm and get an A+, and study 30 hours for another, and fail (happened to me this term). That's just how it works sometimes.

I'm sure you guys have far better ones than me, so go for it!