While runner’s bodies come in all shapes and sizes, I think that if you look at their mental characteristics you will begin to see similarities. Runners typically are mentally tough and have a strong vision and focus.
Why is it that runners have so many similar mental characteristics? It’s because running is a mental sport. In order to be a runner, you’ve got to learn how to master your mind.
This is a perfect metaphor for life and for running. If, while you are running you are envious of how fast someone else is going or feeling self-pity, or telling yourself you're not good enough, you're not to accomplish the goal you've set for yourself, etc, you are steeling your own joy. You will not have fun on your run. You are feeding the evil wolf and if you feed him, he will rule your run and your life.
So as you set out on your next run ask yourself, "Which wolf am I going to feed today?"