Apple Watch now monitors (and notifies you about) low-level cardio fitness

Timed to the launch of its Fitness+ service, Apple has also launched some new features for the Apple Watch. 

Starting with iOS 14.3 and watchOS 7.2, the Apple Watch will monitor a user's cardiorespiratory fitness levels. 

Prior to this update, the Watch measured VO2 max (the maximum amount of oxygen the body can use...