New York Times best-selling author and ultramarathoning legend Dean Karnazes has pushed his body and mind to inconceivable limits, from running in the shoe-melting heat of Death Valley to the lung-freezing cold of the South Pole. He's raced and competed across the globe and once ran 50 marathons, in 50 states, in 50 consecutive days.

In A Runner's High, Karnazes chronicles his extraordinary adventures leading up to his return to the Western States 100-Mile Endurance Run in his mid-50s after first completing the race decades ago. The Western States, infamous for its rugged terrain and extreme temperatures, becomes the most demanding competition of Karnazes's life, a physical and emotional reckoning and a battle to stay true to one's purpose. Confronting his age, his career path, and his life choices, we see Karnazes as we never have before.

For Karnazes, the running experience is about the runner and the trail. It is not the sum of achievements but a story that continues to be told each day, with each step. A Runner's High is at once an endorphin-fueled adventure and a love letter to the sport from one of its most celebrated ambassadors that will leave both casual and serious runners cheering.