The right kind of exercise shoe is important for your feet and other parts of your body as well. I picked up a pair of Asics Gel cross-training shoes without knowing much about what kind of shoe I should buy or what I would need it for, but it has turned out to be my go-to shoe for everything from walking all around the city to working out at the gym. Choose a shoe that is comfortable, provides cushioning, and supports your arch and your level of pronation (the way your foot rolls when it strikes the ground). The look of the sole of your shoes doesn't always give a solid indication of whether it's time to replace them or not. REI offers some advice about determining when to replace your exercise shoes.