Getting more people to exercise on a regular basis and improving athletes' performance are key aspects of sports and exercise psychology. In turn, researchers and practitioners undertake substantial efforts to increase exercise motivation, or to help exercisers deal more adequately with aversive sensations that are often associated with exercising (e.g., effort, pain). One sensation that appears to be particularly important in this context is boredom: Exercisers frequently turn to online message boards to discuss their exercise-induced boredom, and specialized sports media outlets repeatedly post advice on how to make one’s training less boring. This is in stark contrast to the relative scarcity of boredom research in sports and exercise contexts. In this chapter, we draw on current definitions and theories of boredom to explain why boredom matters for sports and exercise. We demonstrate how boredom can deter people from exercise – but also draw them to it. Our overview of the literature covers three distinct sports and exercise contexts where boredom might be relevant. First, we review boredom in the context of physical education, then we cover boredom in recreational sports and exercise settings, and we close our review with a discussion of boredom in performance-oriented sports. In these three different contexts, boredom appears to be a powerful factor that affects sports participation and performance. To conclude, boredom matters for sports and exercise, and further research is needed to better understand its relevance.