Whether you're going to the gym before or after work, or just getting out of the house for a quick workout, you don't want to worry about showing up only to realize you're still wearing work boots or wingtips. Keep a pair of workout shoes in your bag at all times and you won't have to double back to your home to take a second whack at getting prepared -- or decide to park yourself on the couch because it's already too much hassle.
A good pair of cross-training shoes will suit your needs no matter what you do. Whether you decide to lift weights, run on the track, get on the stationary bike, or play a game of basketball or racquetball, cross-trainers won't let you down.
You'll also want to pack a pair of flip-flops so you won't have to stand directly on the locker room floor when you shower or change clothes. Forget your flip-flops and you're asking for a bad case of fungal infection in the form of athlete's foot.