Make sure your Apple Watch and paired iPhone are updated
Turn on Location Services on your iPhone
Turn on Bluetooth and Wi-Fi on your iPhone
Wear your Apple Watch snugly on your wrist
Open the Workout app on your Apple Watch
Choose Outdoor Walk or Outdoor Run
Walk or run outdoors in an open area with good GPS reception
Continue for about 20 minutes at your normal pace
Keep your iPhone with you if needed for better GPS calibration
Repeat the outdoor workout on different days if necessary
Reset calibration data on your iPhone if you want to start over
Open the Watch app on your iPhone
Tap My Watch
Tap Privacy
Tap Reset Fitness Calibration Data
Recalibrate by repeating the outdoor workout steps