Regardless of your plans after your workout, you're going to need a boost of energy. And if you don't think ahead, you may find yourself idling in a long line at a fast-food drive-through as you wait your turn to buy some of the very food that requires you to work so hard in the gym in the first place.
There's a wide variety of protein and energy bars that can be found in almost any grocery store. Buy a few boxes and keep your gym bag stocked with a handful of them (it can be hard to stop at just one, especially if you've tortured your muscles and cardiovascular system as if they had personally insulted you).
Eating a nutrition bar after a workout will give you the boost you need to think clearly and will help your body as it begins the post-workout process of rest and recuperation. And by planning ahead, you'll ensure that the food you snack on while you're at the gym is healthy, unlike most choices found in the standard snack machine.