Problem
I need to turn off the power save mode in my watch
Apple Watch Series 3, watchOS 7
User profile for user:
Community User
To turn off Workout Power Saving Mode,open the Apple Watch app on iPhone, tap My Watch, and then tap on Workout > Power Saving Mode.
Turn the switch off this turns the heart rate monitor back on.
To turn off power reserve mode,press and hold the side button for about 10 seconds, until you see the watch restart and the Apple logo appear.
Keep in mind that if your battery is almost completely empty, you might need to charge the watch before it will restart normally.