Tracking activity increases the satisfaction of exercise. It also assists training for a specific goal, like a marathon or triathlon. When the wearer knows what has been done, they can do more next time. Garmin, an early player in sports watches, now has models that come with smart notifications, contactless payment and the ability to play music. Fitbit trackers monitor heart rate, activity, sleep and the time of day – and now there’s a Fitbit watch with on-screen coaching and music.