This document discusses how to become a self-tracking aficionado by collecting and analyzing personal metrics from devices and apps. It recommends tracking metrics like calories burned, heart rate, sleep patterns, weight, and more to gain insights into habits and optimize performance. Popular self-tracking tools like Fitbit, Withings, and OmniContext apps are introduced that simplify tracking. The document advises applying insights from data by making adjustments and sharing progress within the self-tracking community.