Marathon Fear

So here is just one of the many fears that rattle around when I think about the marathon I registered for, what if running the marathon causes me to injure myself and derails the sport I am trying to incorporate into my life for good?  I've mentioned before that I use DailyMile to track my runs and to connect with other runners and athletes for encouragement and support.  It is a great site and I highly recommend it.  My fear comes from noticing that a number of runners who have already done marathons seem to have sustained injuries that keep coming back to haunt them in their training.  I remember back a few months ago when I was getting really bad hip pain after running.  It turned out that as soon as I started running in new shoes that problem dissipated.  I had read that shoes should last 300 to 500 miles and, being a frugal person, i figured I could get mine to work for 500 miles.  That turned out not to be the case, which was a a disappointment.  So my fear for today is that I will hurt myself, either during training or during the actual marathon, and that whatever that possible injury will be will stop me from being a runner.  Even seeing that in print makes it start to seem a little funny, but there, it is out there.