TIP 901: Where is the only place that your running shoes cannot give you a customized fit?
 
Directly beneath your foot.  

An otc (over-the-counter) orthotic or foot support is a fairly inexpensive and much needed foundation for every shoe and every runner.  Its 3-dimensional shape closely matches the 3-dimensional shape of your foot to enable it to work better and with less stress and strain.  Along with the proper shoe, it can play a major role in improved performance, injury prevention as well as in relieving many existing aches and pains from your foot and sometimes even up to your neck.  It's all about balancing your body so it can function from a more optimal position.   Always try an otc orthotic first before you resort to considering a much more pricey custom orthotic.  It will probably work - and will be better on your pocketbook.  

FOOT SUPPORTS ARE VERY IMPORTANT.  Try to find any professional athlete not wearing them.