Running with the Kenyans by Adharanand Finn. The book focuses on the Kenyan long distance runners and asks the question as to why they have been able to dominate distance running for such a long time. I read the book in 2012 for the first time and then reread it recently as I found this story by Finn so captivating. I guess the reason why it had such an impression on me is because it's a question I've had for as long as I've been watching athletics on TV. The author went to live in Kenya and trained with the best runners in the world. He lived their lifestyle from A-Z (food, training, rest etc.) and tells the story of the Kenyan runners in a very fun and interesting way. I think it's a great read for anyone who is into running or someone who just likes a good true story of how the best runners became the best.