This article reports findings from a program of research on the systematic influence of implicitly perceived facial expressions of emotions on effort mobilization in cognitive tasks. Recently published research on the implicit-affect-primes-effort (IAPE) model (Gendolla, 2012) has revealed replicated evidence for this effect: implicitly perceived facial expressions of sadness, anger, fear, and happiness influence effort-related cardiac response during cognitive performance. In further support of the IAPE model, those studies revealed that the effects of implicitly processed emotional expressions on effort mobilization differ systematically: Implicit fear and sadness expressions that are processed online during task performance render tasks subjectively more difficult, resulting in relatively high effort. Implicit happiness and anger expressions have the opposite effect. Moreover, objective task difficulty and incentive moderated the effect of implicit affect, and especially controlled processing of affect primes turned out to be a boundary condition.