A location-based reminder application is useful only if it can sense the current location information within a reasonable delay time, which inevitably will lead to substantial power consumption in the smartphones/tablets. For example, with the average walking speed of 4.85 ft/s (1.478 m/s) for younger pedestrians [22], it takes about 7 s for a young person to walk 10 m. It means that choosing a strategy such as doing location sensing once 10 s to save energy is unrealistic. In our implementation, we set the period of location sensing to 3 s to achieve the balance of power consumption and response time. Another solution to saving the energy can be doing location sensing only when the user is moving. This can be accomplished by using the built-in accelerometer of the mobile device to detect the movement of users.