I volunteered to do this walk for cancer thing. It's 4 miles. But on the registration paper I have to sign that I attest that I am physically fit and trained for participation of this event. Now, I have walked 4 miles but I don't think it's necessarily a activity that I need to get training for. I am 15 and physically fit but I just want to know what I am getting into. Does anyone have previous experiences and how it was?