A recent release from Netflix's Make It initiative is the Netflix Personal Trainer. According to the company, the small device connects to the user's phone or tablet via Bluetooth and uses and accelerometer to monitor workout activity. If you start slowing down, your personal Netflix-character trainer - e.g. Terry Crews or Queen Elizabeth - will "deliver motivational words to keep you going".
Read more about it - and get the component list to make it - from Mashable.