The body has become central to practices of self-tracking. By focusing on the relations between quantification, the body, and labor, this volume sheds light on the ways in which discourses on data collection and versions of the "corporate self" are instrumental in redefining concepts of labor, including notions of immaterial and free labor in an increasingly virtual work environment. The contributions explore the functions of quantification in conceptualizing the body as a laboring body and examine how quantification contributes to disciplining the body. By doing so, they also inquire how practices of self-tracking, self-monitoring, and self-optimization have evolved historically.