You will go to a small shoe outlet that has a section the size of a small wall for flat feet, a wall for normal arches, and a wall for high arches. You will try on a pair for your arch style and if it fits you WILL buy that shoe. There will be no "do you have it in white with a yellow Nike swoosh" BS. Obviously if it does not fit you will keep trying on a few pairs till you get one that fits. Do not think for a second that a person can go through trying on about ten different pairs. For better or for worse if it fits you WILL buy it. You can bring a pair of "dedicated Running shoes" NOT CROSS TRAINERS with you but you will still have to buy a pair there at basic. The reason that they do it this way is if they didn't then you would have idiots showing up with the "flyest" Air Jordan's which is of course a basketball shoe and then getting slow injuries later on due to the fact that basketball shoes really aren't meant to be logging miles of running in them. Make sense.