In order for an app to share data with Google Fit, you need to connect that app to Google Fit. The exact procedure varies from app to app. However, the basic steps are as follows:
- Open the desired app, e.g. Strava, RunKeeper or MyFitnessPal.
- Open the "Settings" menu.
- Find the setting to connect other apps and devices. Depending on the app, it will have a name like "Link other services", "Apps and devices", "Partner accounts" or "Manage connections".
- Follow the on-screen instructions to connect the app to Google Fit.