Persuasive technology to motivate healthy behavior is a growing area of research within HCI and ubiquitous computing. The emergence of commercial wearable devices for tracking health- and fitness-related activities arguably represents the first widespread adoption of dedicated ubiquitous persuasive technology. The recent ubiquity of commercial systems allows us to learn about their value and use in truly “in the wild” contexts and understand how practices evolve over long-term, naturalistic use. We present a study with 30 participants who had adopted wearable activity-tracking devices of their own volition and had continued to use them for between 3 and 54 months. The findings, which both support and contrast with those of previous research, paint a picture of the evolving benefits and practices surrounding these emerging technologies over long periods of use. They also serve as the basis for design implications for personal informatics technologies for long-term health and fitness support.