Contemporary Quantified Self enthusiasts are tempted by the possibilities of the surveyed body. Thus, Joggers can keep track of their accomplishments, snorers can monitor their sleep, and chronically ill patients can re-adjust their medication. “Self-knowledge through numbers” became the mantra of the emerging communities of self-trackers (Lupton 2014), and Quantified Self, lifelogging, and personal informatics are the terms applied to describe the use of digital technology to track physical activity, quantify bodily processes, and monitor the own conduct of life. While pre-digital precursors to the Quantified Self, e.g. the British “mass observation” movement of the 1930s, or what has been described as “direct observations” by Schütz (1964) a.o., have anticipated what now has become a mass phenomenon, critical historical analysis will have to point out similarities and differences between new forms of digitally enhanced practices and their pre-digital precursors. The proclaimed aim has been and remains body management and control through monitoring and feedback with the ambition to transform the body and its activities into numeric representations that can be stored, addressed, visualized, monitored, processed, transmitted, and evaluated in order to deduce knowledge about the body.