Challenge Friends to an Activity Competition
The Apple Watch tracks all of your activity, and now you can upgrade that by competing with friends in Activity Competitions.
This is a new watchOS 5 feature that lets you set up a 7-day challenge against a contact so that you can get that little bit of extra motivation.
It's a cool way to keep going when you might otherwise slack off at the end of the week.
You both need the Apple Watch, watchOS 5 and one person will need to invite, while the other accepts.