Care and Feeding of Your Apple Watch
It may be a sharp-looking timepiece, but the Apple Watch is also a piece of highly technical electronics. Taking care of it involves more than a polish here and there.
As I mentioned earlier, expect to top off the battery every day or so by connecting the included charging cable to the back of the watch.
If you want to actively conserve battery life, you can manually put the watch into its Power Reserve mode, which shuts down everything but a minimal digital time readout that appears only when you press the side button. This mode also kicks in when the battery level is below 10 percent.
To enable Power Reserve mode manually, swipe up from the bottom of the display to show Control Center, tap the ...