This app for the Fitbit Ionic and Versa helps you use the pomodoro technique, where you work for a specific time and afterwards take a break.
Screenshot Fitbit Ionic:
Screenshot Fitbit Versa:
Via the settings on your phone, you can set the desired time intervals, as well as your preferred colors!
Download the app from Fitbit via: https://gam.fitbit.com/gallery/app/8ce9c902-2158-454f-97ba-7e85a05d193b or directly from their store (soon).