The sensor layer is a collection of off-the-shelf devices that measure the metabolic activity. In particular, we propose to use heart rate, blood pressure, and blood glucose monitors currently available from Alive Technologies25. We also propose to use BodyMedia WMS™ sensors to measure the Galvanic Skin Response (GSR) and motion estimation using accelerometers. In addition to measuring the metabolic activity all these sensors are also capable of wirelessly transmitting this data over Bluetooth interface. We propose to use feature rich Nokia N95 as the mobile phone platform. N95 supports Bluetooth 2.0 +EDR for quick pairing with external Bluetooth sensors, and has 3G and WiFi radios for high bandwidth data transfer. All the external sensors listed above stream data to the Bluetooth enabled N95 mobile phone. In addition to the high bandwidth radio capabilities, the N95 mobile phone platform has a highly accurate built-in assisted GPS unit that uses a combination of GPS satellites, cellular tower and WiFi scanning to obtain a GPS position lock in less than 10 seconds. The stated location accuracy of GPS unit is 30 meters, while in practice the observed accuracy is around 3 meters.