How do I close my rings

Make sure you stand up and move around for a minute at least 12 hours a day, do 30 minutes of brisk exercise (HR at 75% of maximum), keep moving until the red ring is done.

You would need to do some exercise to close your rings. Alternately, you could scroll to the bottom of the Activity app on your watch, click on Change Goals, and then change your goals according to your exercise each day (this is cheating though).

Close Your Rings