I'll see how many of these I can track down. Here is the redoubtable Dr. George Sheehan. I highly recommend his books, especially Dr. Sheehan on Running. It's not a book on how to run faster or longer or even better. It's a book on why we run, what moves and touches us to be runners.
"It's very hard in the beginning to understand that the whole idea is not to beat the other runners. Eventually you learn that the competition is against the little voice inside you that wants you to quit." - George Sheehan
If you are a sales person, I would suggest listening to Blair Singer (or reading the book but I like the CD I have) and his Little Voice Mastery Systems Audio CD.