RecruitingBehavioural interventionAerobic Exercise and Obsessive-Compulsive Disorder SymptomsThe purpose of this study is to examine the acute effects of exercise on cognitive flexibility and symptom reactivity. The main questions it aims to answer are: Does moderate intensity physical activity reduce subjective distress, compulsive urges, and intrusions- and increase cognitive flexibility- in adults with obsessive-compulsive disorder compared to low-intensity physical activity? Researchers will compare low- to moderate-intensity exercise to see if moderate physical activity increases cognitive flexibility and reduces symptom reactivity in adults with obsessive-compulsive disorder (OCD). Participants will: Complete self-report surveys, psychiatric interviews, and cognitive tasks. Be assigned to either a low- or moderate-intensity exercise condition and complete physical activity. Repeat cognitive and symptom measures following the exercise intervention.