Step1:To begin, make sure your device is linked to a Wi-Fi network.
Step 2: Go to Settings > [Your Name] > iCloud on your iPhone. If the control is turned off, turn it on.
Step 3: Select iCloud > iCloud Backup from the menu. If the control is turned off, turn it on.
Step 4: Ensure that the Watch is turned on.
Step 5: Return to the previous screen. Now, if it hasn't been backed up in a while, or just do it anyway for the most recent data record.