Then read this blog.
These are my fantabulous friends, Amanda and Rob, who ran the Disney Marathon and are complete rockstars. I'll let her blog explain the rest because she did such a great job doing it!
I could totally identify with them on all the emotions that you go through (I ran 1 marathon a couple years ago-Marine Corps Marathon). It's a crazy, awesome ride. Everyone should do at least 1 in their lifetime!