This is an eight-month research project using one group pretest-midst-posttest design. This study is based on self-efficacy and self-regulation of Social Cognitive Theory. The investigators will recruit 50 university students with a body mass index of 24 kg/m2 or above at one university campus. Participation is completely voluntary. After pretesting, a 12-week "Mi Band Step Challenge" will be launched immediately. Participants will be assessed with the validated instruments of International Physical Activity Questionnaire (IPAQ)-Taiwan short-form, Sedentary Behavior Questionnaire (SBQ), self-efficacy and self-regulation questionnaires. Mi Band activity trackers will be used to monitor step counts. An ioi 353 body composition analyzer will be used to assess body composition. Data will be analyzed using generalized estimating equation (GEE).

The expected outcomes of this study include: (1) "Mi Band Step Challenge" will be developed based on the theory, which is expected to be effective. If this is true, the intervention can be packaged and applied at different types of colleges and universities with overweight students. (2) "Mi Band Step Challenge" has the potential to be used for the reference of the healthy weight - physical activity, which is embedded in the School Health Promotion Program executed by the Ministry of Education. (3) The result of this study can serve as an example for the promotion of evidence-based health care.

Inclusion Criteria:

• University students with a body mass index of 24 kg/m2 or above at one university campus.
• No physical limitations that would prevent them from performing physical activity.
• Not currently pregnant women.
• Having a smart phone that would allow them to connect to a Mi Band.

Exclusion Criteria:

• The university student who expects to be absent for more than 2 weeks or expects a suspension or transferring to another school during the implementation of the intervention.