With a lightweight watch case that measures just 34 mm, you'll only notice it on your wrist because it looks so good.See your body's energy levels throughout the day so you can find the best times for activity and rest.The watch constantly samples your estimated heart rate and can be set to alert you if it stays too high or too low.Find out if you're having a calm, balanced or stressful day. Relax reminders will even prompt you to do a short breathing activity when you're feeling stressed.