Away from the crushing disapproval of his father, he lived alone in a teepee in the mountains. Everything he needed he built, grew or killed. He made his clothes from deer he killed and skinned before using their sinew as sewing thread. But he didn't stop there. In the years that followed, he stopped at nothing in pursuit of bigger, bolder challenges. He travelled the Mississippi in a handmade wooden canoe; he walked the two-thousand-mile Appalachian Trail; he hiked across the German Alps in trainers; he scaled cliffs in New Zealand.