Introduction: Physical activity participation has dramatic implications to holistic health; however, attempts to promote physical activity through social cognitive approaches alone have limited outcomes. While some believe implicit/affective styles of motivation towards physical activity should be targeted, it remains unclear which exercise-related affective construct might be most salient in predicting exercising affect. Purpose: To identify whether exercise-related affective constructs independently predict subjective responses (affect/ rate of perceived exertion [RPE]) to aerobic exercise in a sample of healthy young adults. Methods: A cross-sectional design was used to assess 15 unique exercise-related affective constructs and subjective responses to exercise across three laboratory visits. Multiple regression analyses were used to identify which construct(s) independently predicted subjective responses during exercise while controlling for relevant covariates. Results: While no independent predictor was found for RPE, desire to rest was found to significantly predict exercising affect, independent of other exercise-related affective constructs, physical activity level, BMI, and concurrently measured RPE while controlling for baseline affect. Conclusion: Future work should explore intervention strategies/techniques that aim to decrease desire to rest before activity occurs, this may lead to improved affective responses to exercise.