As bi-peds our feet are the only body part that consistently comes in contact with the ground. Lacing up the proper training shoes is key to getting the chiseled bod you want without injury. Like the tires on a car, ill-fitting shoes with worn out tread or internal support can result in slips and skids, as well as unneeded strain to the ankles, knees and hips.
Before you shop, consider the activities you'll engage in wearing these shoes. While a standard weight workout in a gym requires less support, running, jumping and many outdoor activities demand more. Additionally, uneven and hard surfaces like concrete and asphalt affect stabilization and more aggressively erode soles. Thus, many trail running and outdoor sport shoes are crafted with wider, more durable, deeper treads. Clearly for turf sports like soccer, football, golf, etc., seek a sport-specific cleat to keep you grounded.
While a person with normal arches can focus entirely on selecting a shoe appropriate for the activity, at least half of us have either high arches or flat feet. Both conditions affect pronation, or how the foot hits, absorbs impact and propels forward, normally rolling from the outer to the inner edge. Exercising and even basic daily activities are more painful and potentially dangerous with either condition, but are largely correctable. For substantial ankle, knee, or low back pain, see a podiatrist, get fitted for orthotic insoles and bring insoles shoe shopping. A high end fitness shoe store will typically have a specialist observe your feet and stride to help with shoe selection. But, knowing you want a DIY solution for every project, examine the soles of a worn pair of sneaks to determine the shape of your foot.