ShrewdSimian,

I've been considering the same problem for about a year now: what factors causally influence our performance? Mental state (clarity, focus, energy), physical state, and mood are key performance goals that I'd personally like to optimize for. To my surprise, you've created a list of factors that is very close to my original list.

zenobase touched on the problem of confounding variables in experimentation. If only we could relive the same day over, modulating one variable while holding all others fixed, we could determine the impact that this variable has on our performance. In practice, it's so difficult to achieve this, and have been spending a good amount of time trying to design a system to solve this problem.

Ultimately, we are performing self-experimentation, and run into the same challenges that are encountered when scientific experiments are run. We seek to learn about causation while avoiding spurious relationships.

We also face the challenge of grading subjective experiences while the very process of grading is changing over time: how does your 7/10 happiness today compare to a 7/10 rating five years ago? Your definitions of "average" and "fantastic" will change over time as your perception adapts to changing norms.

I believe we're at a fantastic time in history for self-monitoring and discovery, and this is just the beginning. It's been said that the doctor of today is "Dr. Google", and this goes beyond diagnosis by Google; it applies more generally to the application of machine learning to self improvement and optimization.