This book of 42.195 insights―the number of kilometers in a marathon―distills the wealth of wisdom and experience Mara has gained as a world-class athlete. From planning training, optimizing nutrition, and preparing effectively for racing to coping with disappointments and struggles with mental illness, Mara shares everything she has learned―good and bad―as one of the world's top marathoners. Still, she does not spoon-feed her readers with training plans; instead, she encourages them to think critically to understand how to improve and set their own goals. This book also takes the reader into the revered world of distance running in Japan, one of the world's marathon superpowers. It has something for everyone, from beginner runners to competitive athletes and those aspiring to the very top.