Small, friendly nudges between breaks. They wait if a break is coming up soon.

Eye rests
Every 20 minutes: look at something 6 m (20 ft) away for 20 seconds. Rest My Eyes in the tray menu is free any time; automatic eye-rest reminders are part of Pro.
Water
A nudge to drink a glass of water, every 15 minutes to 3 hours, toward a daily water goal. Logging water from the tray menu is free; automatic reminders are part of Pro.
Want a nudge for something else? Add your own reminders.
Screenshots are from Windows and Linux. The Mac app has the same settings in its own Settings window.