In this diary study we tested reciprocal relationships between state positive affect and deep acting toward coworkers. We suggest that state positive affect in the morning will provide employees with the positive energy needed to engage in deep acting toward their coworkers during the workday. Deep acting toward coworkers will be rewarded; thus, we hypothesized that coworkers will reciprocate and show more emotional and task support as a response. Coworker support, in turn, was expected to boost well-being, predicting higher state positive affect at the end of the workday. During a two-week diary study, 102 employees answered a general survey and 618 daily surveys. Multilevel path analysis showed that morning state positive affect was positively related to daily deep acting toward coworkers. Moreover, daily deep acting toward coworkers was positively related to more emotional (but not task) support from coworkers, which then predicted higher end-of-work positive affect. Findings highlight the importance in studying emotional labor toward coworkers, as well as the bright side of emotional labor and the potential positive feedback loops that employees can experience at work."