Why do I do it?

Before entering high school, I made a decision that would effect me for the rest of my life. I did not know that my choice would have such a big impact on me at the time, especially since I went on a limb in making it. Joining the cross country team was something that I did so randomly that I do not even know what made me do it today. I had never ran more than a mile, and I was not particularly good at running. I wound up running all four years of high school, and I still run today. Yes, I really sucked at first, and to be honest, I hated going to practices. However, it did not take long until I developed an addiction to running. When I run, I am in a zone. Sometimes I make myself go, but once I am running I never regret.
Everyone always asks me how I can make myself go running for miles; I think it is a feeling that only a runner, or a swimmer probably, can understand and make sense of. I do not run anymore because I have to go to practice and nobody ever made me do, I do it because I truly enjoy it. Running has taught me so much about discipline and doing something just for the sake of doing it. When I am running I think I am experiencing a little bit of the "optimal experience".