Using a mHealth Intervention to Promote Physical Activity in Phase III Cardiac Rehabilitation Clients

In this study, the investigators will implement a pilot project of using activity tracker (i.e., Fitbit) with phase III CR clients. The study will record the clients' daily steps and sleep patterns for 8 consecutive weeks in natural settings. Two specific aims are identified for this project: 1. Develop an intervention protocol using mHealth to promote Phase III CR clients' self-monitoring of PA. 2. Examine the efficacy of the intervention on clients' PA, sleep patterns, functional capacity and QoL.