In the event an app on your Apple Watch stops responding, you can force quit the app instead of restarting your entire device. A feature originally brought to my attention by iMore.
The next time you find yourself staring down the spinning circle of waiting for minutes on end, try this:
Press and hold the side button in (the button just below the Digital Crown) until the shut down screen appears.
Let go of the side button, then press and hold it again.
After a few seconds, a brief animation will return you to the app, then to the home screen of your watch. The end result is the app being closed.
I've yet to actually need to do this, but it's nice to know it's at possible should an issue arise.