In this article, we report the results of a study that was part of a five-study concept development project. Our goal was to learn about the nature of illness by exploring variations in the manifestations of fatigue, a symptom that is prevalent in both ill (cancer, depression, chronic fatigue syndrome) and selected nonill (recreational marathon runners, shift workers) populations. In this article, we report results of our study of recreational marathon runners, obtained from unstructured interviews with 13 runners between the ages 19 and 49 years using ethnoscience as the design. Key findings with implications for practice are the importance of planning recovery periods following large energy expenditures, the value of using dissociative strategies to manage tiredness, and the usefulness of associative strategies and support systems to manage fatigue. Future studies could explore whether these strategies would be useful for management of tiredness and fatigue in other populations.