Watching US President Barack Obama's inauguration speech was inspiring overall but particularly the fundamental truth in this sentence:
"..firm in the knowledge that there is nothing so satisfying to the spirit, so defining of our character, than giving our all to a difficult task..."
This is true for any challenge we face, whether it is out of choice or not. It certainly is a core truth for any runner, regardless of experience or ability.
Whether the goal is to become a runner, or increase the distance we can cover on foot, or improve the time it takes to cover a certain distance, the fundamental reason we enjoy chasing such goals is exactly because of the profound reward described above.