I've learned some things recently that no one mentions will happen to you once you hit your mid twenties:
1. You can get allergies, even if you've never suffered from them before like this crap...
2. You actually have to start thinking about making really large purchases. At 19, the thought of getting a loan for a car made me want to cower under a bed.
3. You can't just eat whatever you want anymore, with no consequences. unfortunately.
4. What is up with going to bed at 10:00 so i can be rested for work? What happened to staying up as late as i wanted and being able to make it the next day just fine?
I'm sure there will be more wonderful surprises to come when I'm 30!