Use the Samsung Health app on your Galaxy Watch3 to keep track of all your fitness goals. To set up the app, simply pair your watch to your phone. As long as you are logged into your Samsung account and using the Samsung Health app on your phone, your data will sync to your watch. Once connected, you can use the trackers on your watch to update your water intake, record your heart rate, start a workout, and much more.

For more on tracking activity with your watch: https://www.samsung.com/us/support/answer/ANS00080302/

source