In describing Quantified Self to my more business-minded friends I’d like to cite some numbers that are evocative of the emerging importance of self-tracking.
What I do is far too much for virtually anyone but a self-obsessed and life-threatened nerd. However, noting one’s ‘essential metrics’ (such as body composition and urine pH & ORP, hsCRP, etc) occasionally - say once a week, a month or even once a year - will give someone a reference if they ever get seriously ill. This on the basis that these signs when healthy will give a reference point for them to get back to from their illness.
“Knowledge of results improves performance” is a well-known engineering rubric, never more so when one’s own health is concerned. If you know you’re out of kilter, it is a good motivator to get back on track.