I read this as a companion piece to Finding Ultra by Rich Roll.
It's a short (60 page) memoir about the author's transition from alcoholism and drug abuse to ultra running. It was interesting because (a) it was very well-written and (b) it's realistic in that the arc of redemption does not complete - at the end of the book the author has stopped drinking but has not stopped using prescription medication and also admits that he is not necessarily any happier than he was before.
A thought-provoking book and a great example of the novella-length Kindle single. It also made me want to find out more about Mishka Shubaly, an intriguing and talented guy who comes across as a sort of latter day Henry Rollins.