Whether people's current motivation levels increase or decline also hinge on their social environment. The current research tightly integrates motivational principles from self-regulation research with social comparison processes. In a preregistered experience sampling study including more than 5,400 social comparison situations from people's everyday life, we investigated how discrepancy assessments between the self and a comparison standard influence people's motivation and affect. Results revealed a nonlinear relationship between negative discrepancies (upward comparisons) and effort investment ("pushing"): Whereas motivational pushing increases with negative discrepancies, more extreme upward comparisons were associated with less pushing, but increased disengagement ("giving up"). The effect of negative discrepancies on pushing motivation was even more pronounced for people perceiving high control in their domain of comparison or when the domain was considered as important. Positive discrepancies (downward comparisons), on the other hand, were related to a reduction in effort ("coasting"). Similarly, emotional responses, such as an increase or decrease in self-esteem, are yet another signal for whether someone needs to invest further effort at a current time. The self-regulatory perspective on social comparison provides a novel framework uniting motivational, emotional, and cognitive processes of social comparison for a better understanding of when social comparison can benefit or hinder people's everyday goal pursuit. (PsycInfo Database Record (c) 2021 APA, all rights reserved).