A 48-inch belt will suffice for walkers, but if you want to run faster than a jog, a 54-inch belt will be preferable. Go even longer if you're taller than 6 feet or have an inseam of at least 32 inches. The best running belts are made of leather or nylon and can be found online and in specialty sports stores. Before you buy a new belt, make sure it's comfortable enough for you. You should be able to fit two fingers between the buckle and your body when standing with your arms by your side. The belt should not cut into your skin anywhere. If it does, you need another one. You will need a belt with some degree of flexibility to fit properly. Otherwise, it will cause problems when you run. Leather belts tend to be more flexible than their nylon counterparts, so if you plan to run frequently, consider buying several pairs of different sizes. The best place to attach a belt is below the hip bones, but it can also be used as a cross-training tool to work other muscles such as the chest, back, and abdomen. Running with no belt at all can be dangerous because you cannot push yourself hard enough to benefit from its effect. However, without a belt, your pants would ride up, showing your underwear which could be uncomfortable and distracting.