LetsMuv is the first watchapp for your Pebble to monitor your activity and track your sleep. LetsMuv will use your Pebble acceleromters to track your movements and calories. It will count your steps, distance walked, workouts and even analyse your sleep.
You will need a Pebble Smartwatch to start monitoring your sleep and activities by using LetsMuv. You can buy one online here: http://getpebble.com