This chapter takes an initial step in presenting the case that a new fitness boom has arrived. The 1970s and 1980s are commonly regarded as a time when fitness ‘boomed’ – for example, in that fitness apparel companies grew more prominent and in that new fitness activities and cultures emerged on the scene. The idea that fitness is thriving anew is in one sense a political economic argument. Fitness technology presents a site for investment for Google, Apple, Microsoft, Facebook, and Nike, among countless others. In another sense, the argument pertains to a qualitative change in ‘what’s possible’ in fitness as a result of technological innovation. The ‘wearability’ of Fitbit brand devices, for example, presents the possibility of boundless self-tracking. This introductory chapter makes the case that a new fitness boom has arrived while also setting up the remainder of this book by theorizing both fitness and technology. Theorizing the latter concept involves reviewing scholarly traditions that see technologies as 1) repressive, 2) productive, and 3) both products of and components in socio-technical relations. The chapter concludes by overviewing the remaining chapters of the book.