This study investigated the percentage of patients with acute myocardial infarction (AMI) who engaged in mild exercise at 6 months after discharge based on the stage of behavior change at discharge. Seventeen patients were categorized in the preparation stage and 16 in the contemplation stage at discharge. Overall, 23.5% of AMI patients in the preparation stage engaged in mild exercise at 6 months after discharge compared with 43.8% of patients in the contemplation stage. No significant difference was observed between the patients in the two groups. This suggests that although the stage of behavior change at discharge in AMI patients in this study differed, the percentage of patients who engaged in mild exercise was the same at 6 months after discharge.