After going on vacation, make sure you are prepared to get through your work day, and be productive. You'll need a few things to ensure you make it!
Go on a great vacation with lots of friends! Have way too much fun.
Fly home the night before you have to go to work. In an ideal world, you would take a whole day off at home to unpack, relax, and recharge. I almost never do this because I want to spend as much time on vacation as possible!
Wake up early to get ready for work. Make sure you go in with a game plan of what you want to accomplish (namely getting through all your emails, and what tasks you need to get done).
Drink lots of caffeine throughout the day. You may not even notice that you're hitting a wall, so make sure to stay caffeinated!