Geoff gives great insight into how to train for a 100 miler. One thing I am learning little by little is that even if you may get great nuggets of information from those who have already done this distance, in the end, it is up to you to figure out what will work for you in an extreme event like this. Every runner's needs are different, and that is amplified at this distance. In the end, you have to experiment with many things before you find the combination of factors that work for you. You have to accept the very real possibility of failure every time you attempt an ultra-distance race. You never really know what the day will bring when you are out there for that long, and you don't know how your body will respond to all of your training until the time comes. When people ask me why I run 100 milers, my answer is simple - "When I line up at the start line, I honestly have no idea if I will make it to the finish line." That's where the fun is.