How does Apple Watch work with Health app exactly?
In the Health app, I can see it has both my iPhone 6 Plus and my Apple Watch as the source devices. But I don't think the app is picking up activities from the Apple Watch. I knew this because today when I was playing tennis with my Apple Watch, the activity chart dropped substantially, because my iPhone was somewhere else not moving. So can anyone share how the Watch is supposed to work with the Health app? Many thanks in advance.
Apple Watch