Lace up your sneakers and run around the block. Do that about 10 times and it's a mile. Do that 100 times and it's an ultra-marathon. Now run those 100 miles up a mountain, or in the woods at night, or in a desert so hot that the soles of your shoes begin to melt. Sound like fun? Chris McDougall, author of Born to Run, thinks so. What started as a simple quest to explain a running injury took the former war correspondent deep into the world of ultra-running — and into the world of the Tarahumara, an indigenous race of superrunners who live deep in a canyon in Mexico. McDougall talked to TIME about his experiences and what he thinks about people who say they don't like to run.