On the controls page you can Pause/Resume, End the run, open Settings, or turn on Water Lock.
Ending: tap End and confirm. Your progress is saved.
Auto-pause: optionally pause automatically when you stop (toggle in Settings).
Water Lock: locks the screen against accidental taps (e.g. in rain). Swipe up to unlock.
Screen always-on keeps your stats visible during the run.
The hardware back button won't end your run by accident. You'll be asked to confirm.