Although boredom poses serious consequences for employees and organizations, research has paid little attention to this phenomenon, especially when compared to other job experiences such as overload. Building upon the Effort-Recovery Model, our study examines the impact of these two sub-optimal experiences, characterized by under- and over-stimulation, on burnout via three facets of rumination. Using a time lagged design with three measurement moments and a sample of 152 participants, we found partial support for our hypotheses. Boredom and overload led to emotional exhaustion and disengagement 2 weeks later, via an increase in affective rumination. Overload also increased emotional exhaustion via reduced detachment, yet boredom reduced emotional exhaustion by facilitating detachment. These findings stress the importance of addressing boredom as a pervasive, although often silent, workplace phenomenon.