A wearable electronic device includes a housing and a band attached to the housing. The band has an indicator with a variably and/or progressively illuminable portion. The indicator of the band conveys to a user an analog representation of the completion progress of an activity or task tracked by wearable electronic device. The wearable electronic device also includes a processing unit within the housing, and a sensor operatively coupled to the processing unit. In some cases, the sensor is a motion sensor such as an accelerometer or a gyroscope. In other examples, the sensor is a health sensor or a biometric sensor. Sensor data is used to update the indicator.