Engineering the First Fitbit: The Fitness Tracker's Creators Had a Billion-Dollar Idea—and a Lot to Learn About Hardware

It was December 2006. Twenty-nine-year-old entrepreneur James Park had just purchased a Wii game system. It included the Wii Nunchuk, a US $29 handheld controller with motion sensors that let game players interact by moving their bodies–swinging at a baseball, say, or boxing with a virtual partner.