True, imagine this:
You step onto the Apple treadmill wearing your Apple smartwatch. The watch transmits your heart rate and mood to the treadmill which projects a running path to your AppleTV based on what you're feeling like - new Genius feature. Then as you start to walk or run, you are on the virtual path set out for you projected through AppleTV - up a mountain side, along a beach. Your music is of course intrinsic to all of this. Birds are chirping and life is wonderful. Just don't stop and pee in the bushes.