The goal rings from the Activity app on the Apple Watch should be familiar with many iOS (and Apple Watch) users who have seen it in action or read about and seen it online. It's effective to a point and most people find them useful. However, since I make it a point of getting of my desk a few times an hour at work, I rarely get a notification to get off my butt and move. I can see some people who do need to be pushed to move around a bit after sedentary for a while. The active minutes ring is also very important for those who do not move around enough. Neither of those are an issue for me. I find the active calories more important and trying to reach my 900 daily calories has helped me greatly.
What has been driving me is keeping up the streak of days that I have hit that goal. And while that has been important and helps me lose about 3-4 pounds since I started wearing the Apple Watch a little less than two months ago, I hope Apple will have other health and exercise related measurements and goals for users to follow - maybe even allow users to add a few rings or replace default measurements with user preferences.
I have found the Nike Fuel points to be effective when I wore the Nike Fuel Band. I have ben very disappointed in the lackluster support from Apple and Nike to integrate more Nike features for the watch. While 900 calories a day is nothing to sneeze at, I enjoined trying to reach my 4000 NF points daily (failing for the most part but I enjoy trying) when I used the Fuel Band. Adding a ring for keeping track of Nike Fuel points is a quick example I can think of. Perhaps, some users rather keep track of distance they walk or run each day would rather trying to go the distance every day than using other metrics.
Speaking of other metrics, it would be great for Apple to make this customizable.