One of my favorite running books is by George Sheehan, often called the philosopher of running. I came across Running and Being in my second year of running, so I had some experience to reflect back on. Many of the references to marathons and road races were somewhat lost on me, as well as the discussions of the running boom in the 70's.
What I did find very rewarding were the discussions of why we run, the different states of being when running, and how running shapes us as people and our lives. I'll admit that I majored in philosophy at UCLA so I have a philosophical perspective in general. Although I considered it, I don't think Dr. Sheehan's book took its inspiring title from Martin Heidegger's Being and Time, which I had read a bit of in college. Certainly, I had a lot more fun, and gained significantly more insight into "Being" from Dr. Sheehan than I did from the stodgy German existentialist philosopher. Nothing against Heidegger. He just probably didn't run.
One of my favorite quotes from Dr. Sheehan's book is "Happiness is different from pleasure. Happiness has something to do with struggling and enduring and accomplishing.” So much else in life follows from this simple precept. It is similar to another favorite quote of mine from Marcus Aurelius, found in his notebooks which eventually were published as The Meditations - "The art of living is more like wrestling than dancing, in so far as it stands ready against the accidental and the unforeseen, and is not apt to fall." He I surmise was once a runner.