The Wellbeing app uses your phone’s time to determine whether or not you have succeeded in your challenges. Make sure you sync the wellbeing app prior to changing time zones to ensure you’re properly awarded for the challenges you’ve met. To sync your Wellbeing App, simply open app with your phone connected to the internet. If you have a wearable (e.g. FitBit, Garmin, or Apple Watch), make sure your wearable has synced with its respective app.
When you connect to the internet in the new time zone, the Wellbeing App will sync and associate all recent data with the new timezone. If you have not opened your app for a few days, and open it after you change time zones, your data from the past few days will be processed as occurring in the new time zone.