I am diagnosed with schizoaffective disorder, but manage my illness fairly well.
Dietary and exercise tracking has been a great help help to me. I started with MyFitnessPal for about 2 years but have since started using my own calorie tracker which I made using rfo-basic: https://play.google.com/store/apps/details?id=com.rfo.speakcc
I also developed this app to help assess my wellness:
I haven't made it quantitative yet, but keeping a Done List seems to help me with negative symptoms: https://play.google.com/store/apps/details?id=com.rfo.DoneList ...The number of tasks you accomplish each day probably will fall on a bell curve like everything else.
My positive symptoms are pretty stable but do seem very correlated to negative moods. I have just started using a mood tracker Daylio and like it a lot since it gives me some hope and perspective on days when I am not feeling well.
Also...Although doctors don't generally talk about money issues, financial tracking tools like Quicken and Mint are very important as part of my stress management since I tend to fret when I owe money.
I would say managing any mental illness is mostly about qualitative changes though: having a safe environment, reasonable responsibilties, good relationships, basic living skills, curbing addictive behaviors, setting realistic goals, and simply waiting a very long time.
Best of Luck!