This study examined psychological differences between individuals (1) with varying perceptions of their exercise adherence pattern and (2) who do and do not make exercise-related cognitive errors. A total of 364 adults completed an exercise pattern and cognitive errors questionnaire. Individuals perceiving themselves as consistent exercisers reported more adaptive social cognitive outcomes (e.g. higher self-regulatory efficacy) than those perceiving themselves as inconsistent. Individuals expressing stronger exercise-related cognitive errors exercised less and reported problematic cognitions (e.g. more struggle with exercise decisions). These results link inconsistent adherence perceptions to weaker social cognitions and exercise-related cognitive errors, a novel form of bias related to limited exercise engagement.