The purpose of this study was to increase the duration of treadmill walking to reach moderate exercise intensity level for a 26-year-old male diagnosed with moderate autism spectrum disorder (ASD) accompanying an intellectual disability. We used a structured system including token reward system of visual representation of progress. A changing criterion single case research design was used and was consisted of the baseline phase, three sub-criteria intervention phase, and follow-up phase. Results showed that a functional relationship was established by demonstrating and replicating effects throughout the three sub-intervention phases. In addition, there was an increase of 173% (>2 standard deviations) from the original base-line duration and 93% of duration were at the moderate exercise intensity. This study may be of importance that the intervention may built up the health behavior and lifestyle of the participant with ASD. Further replicating studies are suggested.