My Apple Watch and Apple Fitness app are not syncing

When I try to use the Apple Fitness app on my Apple TV or iPhone or iPad it doesn't always pair with my Apple Watch. When it does work it takes several minutes to pair. The watch is never far from the device (less than 5 feet) and all devices have been rebooted and the Fitness app uninstalled and reinstalled. This problem started a couple of weeks ago. HELP!