Want to feel good?

Why do we run? Is it for the solitude, for the peace of mind or for the thrill of competition? Is it healthy to want to run a marathon or a sign of desperation for overachievement? Perhaps it's all of the above and a lot more. All I know is that hurting my knee yesterday denied me the chance to go for a long run this weekend - and that makes me cranky. Roll on the healing process!