Apple's iPhone is going from part-time health stat monitor to full-time mobile monitoring unit. HealthKit is a new service coming to the iPhone that tracks, records and analyzes your fitness level across a variety of metrics (sleep, movement, etc.). The way you use it on iOS 8 is through a new app called, simply, "Health." The initiative works with companies like Nike to bring all your health information into one place, under the Health app in the next update to iOS. It looks a lot like Passbook, using cards to identify various stats. Thusly, it enables customization of the stats you want tracked and how you want it presented.

http://www.engadget.com/2014/06/02/apple-healthkit/