There are several fitness apps already available for the iPhone, but they often cost money to use. If you want a free one, try Google's new app.
Google Fit, Google's own fitness tracking mobile app for Android devices, has finally arrived on iOS. It not only works on iPhone but also syncs with both the Apple Watch and Wear OS devices. It supports Apple Health, too. That means all the progress in every Apple Health-supported apps you use, whether that be Nike Run Club or Headspace, will count toward your Google Fit goals.
The Google Fit for iOS app offers you activity goals based on recommendations from the American Heart Association and World Health Organization. The point is to build smarter, healthier habits and reach the AHA and WHO’s recommended amount of weekly physical activity. You're supposed to hit about 150 minutes of moderate activity a week, and 75 minutes of vigorous activity.
In a blog post, Google said the more you move, the more "Move Minutes" you earn, and the more intensely you move, the more "Heart Points" you earn. You can check your journal in the app to track progress on these activity goals.
Some of this functionality was already available in the Fit section of the Wear OS app for anyone with a Wear OS smartwatch, but now, Apple device owners get their own standalone app that they can download from the App Store.