Here's a nifty little quote I picked up off of Dean Karnazes' Blog.
The Marathon is not about running, it is about salvation. We spend so much of our lives doubting ourselves, thinking we’re not good enough, not strong enough, not made of the right stuff. The Marathon is an opportunity for redemption. “Opportunity,” because the outcome is uncertain. “Opportunity,” because it is up to you, and only you, to make it happen.
There is no luck involved in finishing a marathon, the ingredients required to tackle this formidable challenge are straightforward: commitment, sacrifice, grit, and raw determination. Plain and simple.