This study examined whether affect and prior physical activity influence expected effort of future physical activity, and whether prior physical activity moderates the relationship between affect and expected effort. Affect was manipulated using three affect-inducing scenarios (negative, neutral, positive), after which expected effort and participants’ prior physical activity were measured. The results provided supporting evidence that affect is related to expected effort: higher negative affect and smaller increases in positive affect were related to higher expected effort. However, prior physical activity neither predicted expected effort nor moderated the relationship between affect and expected effort. Overall, the findings indicate that affect can influence expected effort, but they do not support the hypothesis that prior physical activity moderates this relationship.