Past research has conceptualized secrecy as speech inhibition during social interaction. In contrast, the current research broadens the understanding of secrecy by conceptualizing it as the commitment to conceal information. Seven experiments demonstrate the implications of this broader conceptualization for understanding secrecy’s consequences. The results demonstrate that thinking about secrets—relative to thinking about personal information unknown by others that is not purposefully concealed (i.e., undisclosed information)—indirectly increases the experience of fatigue by evoking feelings of isolation and a motivational conflict with one’s affiliation goals. Furthermore, we demonstrate that the fatiguing effects of secrecy have consequences for task persistence and performance. Integrating theories of motivation, fatigue, and social isolation, we offer new directions for research on secrecy.