From a watch face, swipe up to access Control Center.
On some watch faces, you can add a complication to show the current battery charge.
Tap the Battery Percentage.
Drag the POWER RESERVE slider to turn Power Reserve on.
Tap Proceed.
To turn off Power Reserve, press and hold the Side button until you see the Apple logo.
Wait for your Apple Watch to restart. You might need to charge your Apple Watch first.
You've completed the steps!
