Action Button Support!
- Press once when you hear the warning signal to start the timer.
- Press again to sync time.
- Press the Action Button and the side button together to pause.
- Press them again to reset the timer, ready for a new countdown.

Make sure to allow Apple Health to fully utilize the Action Button. Permission is required before the Action Button can start a workout and thus a countdown. The app does not store anything in Health or read any data — unless you enable it in settings.