Use a timer
The Timer app on Apple Watch can help you keep track of time. Set timers up to 24 hours.
Ask Siri. “Set timer for 20 minutes.”
Set a timer. Open Timer , tap hours or minutes, turn the Digital Crown to adjust, then tap Start.
Set a timer for longer than 12 hours. While adjusting the timer, firmly press the display, then tap 24.
Add a timer to your watch face. If you use a timer often, add one to your watch face. With the watch face showing, firmly press the display, then tap Customize. Swipe left until you can select individual complications, tap the one you’d like to use for the timer, then turn the Digital Crown to choose the timer. When you’re finished, press the Digital Crown. You can add a timer to these faces: Chronograph, Color, Mickey Mouse, Modular, Simple, and Utility.