You can link your Google Fit account to your Withings account from the Health Mate app. To do so, you need to:

1. Make sure the Google Fit app is installed on your smartphone.
2. Open the Health Mate app.
3. Go to Profile.
4. Tap Google Fit.
   
5. Tap the toggle to activate the Google Fit integration.
6. Select the Google account you want to link your Withings account to.
7. Tap OK twice.