A mobile device includes a motion sensor configured to acquire motion data, a light sensor configured to detect an ambient light level and generate light data, and a processing circuit. The processing circuit is configured to receive the motion data from the motion sensor, receive the light data from the light sensor, analyze the motion data to determine displacement data corresponding to a displacement of the mobile device, analyze the light data to detect a light transition, and analyze the displacement data and the light transition to determine whether to initiate an action.