Best practices
In a watchOS fitness app, use workout sessions to provide useful data and relevant controls.
Avoid distracting people from a workout with information that’s not relevant.
Use a distinct visual appearance to indicate an active workout.
Provide workout controls that are easy to find and tap.
Help people understand the health information your app records if sensor data is unavailable during a workout.
Provide a summary at the end of a session.
Discard extremely brief workout sessions.
Make sure text is legible for when people are in motion.
Use Activity rings correctly.
For the complete guidance, including worked examples and illustrations, see the canonical page: https://developer.apple.com/design/human-interface-guidelines/workouts