Mood tracking

Was studying about mood tracking, how important do you think it is?

That we can measure we can improve, and mood problems sure are big. E.g. they account for #2 (depressed) and #3 (anxious) symptoms on PatientsLikeMe

So it is probably key to track mood. I would think 1 challenge is that many of these mood states do not inspire you to go and quantitate yourself.