Physical inactivity has been identified as one of the main causes of premature death and many chronic diseases such as cancer, cardiovascular disease, stroke, type 2 diabetes, some cancers, and obesity. Technology plays a complicated role in physical inactivity—much like a double-edged sword. On one hand, some technologies, such as sedentary video games, TV and computers, have contributed to the epidemic of physical inactivity and sedentary leisure-time behavior (e.g., playing sedentary video games). Conversely, some newly emerged technologies have been increasingly used to assess and promote physical activity (PA) and health. For example, pedometers and accelerometers have been extensively used as tools in assessing and promoting PA among various populations. Within the past decade, emerging technology including online social media, mobile devices applications, health wearable devices, GPS, GIS, and AVGs have been used to promote PA participation. Therefore, although technology has potential negative effects on a healthy and active lifestyle, technology does also have great possibilities to facilitate PA promotion.