Understanding intention–behaviour relations is important in physical activity (PA) research given the large number of people who intend to be active but fail to translate these intentions into behaviour. The purpose of this study was to evaluate whether processes/cues for popular sedentary leisure-time behaviours and PA explain additional variance in PA behaviour after controlling for PA intention, and to evaluate whether these processes moderate PA intention–behaviour relations.Random population-based cross-sectional survey.Participants were a random sample of 206 adults who completed measures of the processes of change pertaining to physical activity and four popular leisure-time behaviours (TV viewing, computer use, sedentary hobbies, and sedentary socializing) and an adapted Godin Leisure-Time Exercise Questionnaire.Results using hierarchical ordinary least-squares regression provided evidence that cognitive TV processes explain additional variance in PA behaviour and moderate PA intention–behaviour relations.These results extend the prior literature on relationships between sedentary cognitions and physical activity and underscore the potential value of adding sedentary control interventions in concert with physical activity promotion.