Imagine yourself walking to the gym in the rain after a long hard day at work. Picture yourself lifting heavy weights, even though you would prefer sitting on the sofa watching your favorite baseball team win a playoff match. This is just one sports-related example during which self-control processes enable us to keep striving for a desirable goal and suppress potentially tempting action alternatives. In general, "self-control refers to the capacity for altering one's own responses, especially to bring them into line with standards such as ideals, values, morals, and social expectations, and to support the pursuit of long-term goals" (Baumeister, Vohs, & Tice, 2007, p. 351) 1 . However, self-control is not always applied effectively as, for instance, evidenced by the large number of gym dropouts every year (e.g., Englert & Rummel, 2016).In this chapter, we will discuss empirical findings that highlight the importance of selfcontrol for sports-related performance and we will introduce the theoretical accounts that try to explain why self-control sometimes appears to fail. Finally, we will discuss open research questions in order to improve our understanding of how self-control operates and why it is not applied at all times.
Self-control and the Sensation of EffortResearch on self-control has a long tradition: Narcissus Ach conducted the first studies on self-control already in the beginning of the 20 th century (Ach, 1905(Ach, , 1935. In general, there is a common agreement amongst researchers that exerting control over the self can be a tiring and unpleasant experience. In the mid-20 th century, Hull already stated that impulses or response tendencies have a motivational strength, suggesting that in order to resist these tendencies one must invest some kind of effort or willpower (Hull, 1943). Thus, the application of self-control is intrinsically linked to the sensation of effort (e.g., Kurzban, 2016;Shenhav et al. 2017). This sensation commonly refers to "the particular feeling of that energy being exerted" and is associated with "a sensation of strain and labor, a feeling that intensifies the harder a person tries" (Preston & Wegner, 2009, p. 570). This feeling of work is associated with voluntary actions and provides crucial information for the judgement of personal actions (Preston & Wegner, 2009).