Fitbit charge 5 + premium connects the dots between your activity, sleep, and stress so you can make the best decisions for your body, mind, and health. It all starts with your six-month Fitbit premium membership and daily readiness, a score based on activity, sleep, and heart rate variability (HRV) that helps you optimize your workout routine. Your score comes with personalized activity recommendations low means go easy and recover light yoga, and deep breathing while a high score gives you the green light to go all out.