Scholars have paid an increasing amount of attention to organizational citizenship behaviors (OCBs), with a particular emphasis on helping others at work. In addition, recent empirical work has focused on how OCB is an intraindividual phenomenon, such that employees vary daily in the extent to which they help others. However, one limitation of this research has been an overemphasis on well‐being consequences associated with daily helping (e.g., changes in affect and mental depletion) and far less attention on behavioral outcomes. In this study, we develop a self‐regulatory framework that articulates how helping others at work is a depleting experience that can lead to a reduction in subsequent acts of helping others, and an increase in behaviors aimed at helping oneself (i.e., engaging in political acts). We further theorize how two individual differences—prevention focus and political skill—serve as cross‐level moderators of these relations. In an experience sampling study of 91 full‐time employees across 10 consecutive workdays, our results illustrate that helping is a depleting act that makes individuals more likely to engage in self‐serving acts and less likely to help others. Moreover, the relation of helping acts with depletion is strengthened for employees who have higher levels of prevention focus.