Wearables, mobile apps, and self-tracking interventions are increasingly designed to help consumers optimize various life aspects through self-quantification (SQ). SQ describes an individual’s goal-driven activity of tracking, monitoring and interpreting self-produced numerical data. Tracking workouts, sleep cycles, and diets leads to an overall “fitness age”, for instance. However, the key question remains whether these technologies and SQ truly help individuals improve themselves. What factors drive or hinder the acceptance of these tools, and how can they foster positive user outcomes? This chapter argues that SQ offers opportunities for optimization not only in health but also in areas like financial well-being and sustainability behavior. It explores the tools available and questions the responsibility of marketing in this context, and how it should address its role concerning both consumers and society. Drawing on multidisciplinary literature, this chapter provides insights to rethink the marketing of SQ and its broader societal implications.