Background and objectives: Fatigue is an adaptive state after prolonged effort and often goes hand in hand with changes in behavior and motivation, such as the urge to stop exerting further effort. However, fatigue may become chronic in nature, as seen in multiple psychiatric disorders and chronic diseases, thereby losing its adaptive function. The etiology of fatigue symptoms remains poorly understood. We aimed to investigate whether nocebo information about the fatigue inducing nature of a cognitive task may contribute to the experience of fatigue and the motivational urge to stop. Methods: Participants (N = 46) repeatedly rated currently experienced fatigue while engaging in cognitive effort (working memory task). Crucially, half of participants received nocebo instructions prior to this task, whereas the other half only received neutral information. Results: Over the entire sample, results showed an increase in fatigue and urge to stop as the task progressed. Crucially, participants in the nocebo condition reported a higher urge to stop throughout the task relative to participants in the neutral condition. No significant effects were found for fatigue. Interestingly however, after controlling for baseline differences between conditions in negative affect, there was a significant Condition*Task block interaction effect on fatigue. Limitations: Limitations include the relatively short experimental protocol and the underrepresentation of male relative to female participants. Conclusions: These findings suggest that heightened awareness among clinicians and therapists about potential nocebo effects in their communication is warranted.