The present thesis investigated the role of prime awareness as a moderator of affect priming in the context of effort mobilization. Based on the Implicit-Affect-Primes-Effort model (Gendolla, 2012), which make predictions about implicit affect primes' effect on mental effort, I investigated the role of prime visibility and prime warning as potential boundary conditions of affective influences on effort-related cardiovascular response. To do this, four experiments are reported. Cardiac pre-ejection period (PEP), systolic and diastolic blood pressure, and heart rate were recorded to assess effort-related cardiovascular response. Additionally, to monitor performance, we assessed reaction times and response accuracy.