1. Getting out of bed when you don't want to.
Every morning that you dragged yourself out of bed for school, cursing the world was preparation for every day that you'll drag yourself out of bed for work for the rest of your life. Or until you're 65. Set six alarms, get yourself some caffeine and paste on a smile. No one is really a morning person, they've just trained themselves to think that way, and eventually you will too.
2. Being polite to people you don't like.
The teacher assigns your seat – next to the weird kid you really don't like and then asks you to do an assignment together. Of course you don't want to, but you suck it up and get on with it anyway,just like you'll have to do every single day in your job. Realisticly, they people you don't like are probably well aware that you're not a fan, but the fact that you're making the effort goes a long way.
3. Letting those in authority be right, even if they're wrong.
Bosses, police, bouncers and that one very strict teacher who terrified everyone – sometimes you have to know when to smile, nod and keep your mouth shut. In school its lines, detention or -god forbid- a call to your parents, in the real world its getting fired, arrested or being denied alcohol. This doesn't mean be a pushover, it just means pick your battles. If your boss is about to make a mistake that puts your job at risk, by all means, pull them aside and say it as nicely as possible. If your boss is venting, just let it go.
4. It doesn't stop when you get home.
When you're in school you get homework and you cant understand why, after doing stuff all day, you have to do more when you get home. In a few years its unpaid over time, giving up your day off to cover a shift for some one who swears they'll do it for you, your boss calling to ask you about this file, or that product. Its sleepless nights during busy times because you don't have time to relax between getting in late and heading out early. It never ends.
5. People will judge you on how you look
The image you project will often determine how you're treated, in school, like in a large company, no one has time to get to know everyone for the special snowflake they are. So they look at what you chose to project about yourself. If you look like you didn't make an effort, they'll assume you didn't make an effort. Looking like you made an effort covers a multitude of sins.
6. Doing things you outright hate.
For me it was french, maths and geography. Everyone had subjects they hated, whether it was down to the subject itself or the person teaching it. Its no different at work. There'll be something you just hate doing, no matter how much you love your job. And it will probably be something that's fairly essential. If you work in an office, maybe its filing. If you're a chef, maybe it de-boning fish. Whoever you are, whatever you do, one aspect of it will annoy the hell out of you.