The Jaybird Reign doesn’t just tell you about your workout -- it tells you when to exercise. The wristband features a heart rate sensor that learns about you and your habits to suggest the ideal time for a workout. Not only does it monitor your physical activity such as walking, swimming, or running, but it can also automatically detect when you switch between activities. Additionally, it will also track your sleep, and suggest if you need more rest, which we all do. Due out this spring, the Jaybird Reign will cost $199.