"Thru-hiking," where an individual hikes the entire length of an extended trail, has increased exponentially in recent years, creating a subgroup of trail users that outdoor recreation professionals currently have little knowledge about. Understanding the physiological and psychological demands of thru-hiking, where physical challenges are magnified by adverse conditions, may lend insight into who undertakes a thru-hike, what motivates them, and what physical and psychological benefits they experience. This study explored the experiences of a 26-year-old healthy male on a thru-hike of the Pacific Crest Trail. Data were collected using standard physiological assessments and an in-depth semistructured interview. Results indicated limited improvements in cardiopulmonary efficiency, high levels of autonomous motivation, resilience, and positive psychological outcomes. In physically fit individuals, it is possible that success in thru-hiking is primarily psychological in nature; future research should focus on these constructs in a larger sample of thru-hikers.