Sufficient physical activity can introduce many health benefits and reduce the risk of many chronic diseases such as coronary heart disease, type 2 diabetes, and cognitive impairment. Physical activity can improve bodily health as well as cognitive function and increase life expectancy. Unfortunately, physical inactivity is around world. Increased physical activity has become an important personal health issue in recent years. Context-aware prompting system can integrate information of activity and activity level to reason subject physical activity condition. Based on the condition, a message is generated to notify subject for improving physical activity. This paper proposed a context-aware prompting system to maintain or increase physical activity for personal healthcare management. The proposed mechanism utilizes a smart phone to collect activity context and transmit to remote server for context-aware. The system would generate a message to notify subject based on the context to suggest subject improve physical activity. The preliminary results show good performance of context collection and provide context-aware prompting service to improve physical activity. It fulfills the requirement of personal healthcare management goal to achieve sufficient physical activity.