Bernd Heinrich - Professor of Biology, holder of a world record and several US records in marathon races, physiologist, specialist in thermoregulation and exercise. In this book, he reflects on sports running as a scientist in the field of natural sciences, talks about his participation in the 100 km race, which marked the beginning of his career in the ultramarathon, and draws parallels between man and the rest of the animal world. Endurance, intelligence, the will to win - this is the main motto of runners in super marathon distances, capable of leading to the highest achievements.