This article informs about the implicit-affect-primes-effort (IAPE) model—a theory on the impact of implicit affect on resource mobilization—and research testing this account. Beside basic influences of implicitly processed affective stimuli on behavior, this article highlights moderators and boundary conditions of this process. The IAPE model posits that affect primes implicitly activate mental representations of affective states containing information about performance ease and difficulty. This influences subjective task demand during performance, which determines effort. A series of experiments assessing implicit affect's impact on effort-related cardiovascular response in cognitive tasks revealed replicated support for the IAPE model. Moreover, objective task difficulty and incentive moderated the effect of implicit affect on effort, and especially controlled processing of affect primes and activated concepts turned out to be boundary conditions.