What prompts breathe reminders on an Apple Watch? WatchOS 3 included a breathe app that gives occasional reminders to "take a minute to breathe".

What prompts these reminders? Does it monitor your heart rate to know when you're stressed, or does it remind you at preset times?
By default, breathe reminders are set to display every 5 hours. According to Apple, you can adjust or disable the reminders by doing the following.


  
  Open the Apple Watch app on your iPhone and tap the My Watch tab.
  Tap Breathe > Breathe Reminders.
  Choose how often you get reminders.