How do you feel? Are you feeling better than yesterday? Than last week? Are you overall feeling increasingly better? Is there some part of your life you would like to improve? Or maybe, should improve?
In psychology it’s common with questionares the patients have to fill in at an intervall. For regular people a simple app would suffice. All it needs is a simple tap to save the mood.
The mood, or well being, could be distributed along several axis, like a radar chart. Then once in a while you could check a summary type screen which shows how you’ve been progressing through time. It could be various line charts, or just animate a radar chart. It could even email you the status every week if you want.