This research extends the literature on well-being and performance behavior by looking at how daily fluctuations in employee exhaustion impact performance behaviors. Specifically, we tested a model based on conservation of resources theory (COR) where we predicted that daily fluctuations in exhaustion would be positively associated with organizational citizenship behaviors targeted at coworkers (OCB-I) but negatively associated with in-role performance and organizational citizenship behaviors targeted at the organization (OCB-O); further, we predicted that these relationships would be stronger for employees who perceived a lack of reciprocity in their relationship such that they contributed less or gained more than their coworker (called positive inequity). In two studies including a total of 354 employees from a variety of industries over five time periods over the duration of a week, we found support for the positive relationship between exhaustion and OCB-I, the negative relationships between of exhaustion and in-role performance and OCB-O, as well as the moderation effect of reciprocity. We discuss the implications of this finding for the manner in which employees strategically invest their resources in order to regain their well-being. Copyright © 2011 John Wiley & Sons, Ltd.