Meet the Jawbone UP4: a new fitness tracker that lets you make AMEX payments from your wrist. It has sensors for activity, sleep, and heart health tracking. To get started, just connect your UP4 wearable to an eligible American Express card, and you are set. To pay, just tap the symbol on the bottom of your UP4 on the contactless reader, and you are set. You will be able to get yours for $199.99 this summer.