Running fears, real and imaginary

Warning: this topic degenerates into talk about zombies.

As frequently as I run, I have almost never run scared. Not that I want to run with the fear of god in me, but it occurred to me that most people, including pros, set out to run distance X with effort Y and pain level Z and usually follow through to a tee. Race winners work hard but look relaxed. My idle thought was to imagine how often runners use their skills -however unexpectedly- to save their very lives?