Ultramarathon running entails coping with unanticipated environmental circumstances and intense physical and psychological fatigue; a sport in which the role of mental toughness can be crucial. This research focused on semistructured interviews with 12 ultramarathon runners who volunteered to discuss their perceptions of mental toughness. The data allowed researchers to gather a multidimensional view of mental toughness from ultramarathon runners’ experiences and perspective in addition to providing a snapshot of the challenges and demands ultrarunners face, as well as ethical concerns associated with athletes pushing themselves beyond their limits. Central themes included: perseverance/persistence, overcoming adversity, perspective, life experience, psychological skills use, and camaraderie in the ultra community. A deeper understanding of mental toughness obtained from a sample of ultramarathon runners can inform consultants working to improve quality or consistency of performance, and become aware of ethical concerns of encouraging athletes to exceed perceptual or actual limitations.