With the rapid development of wearable technologies, people can nowadays easily track and record their health-related information—particularly their athletic performance. The quantified-self 2.0 (QS 2.0) movement encourages running website or mobile application users to share their athletic information with other online community members to ensure the sustainable use of the technology and the maintenance of physical activity. However, the health literature claims that health behavior maintenance is difficult because it is easy for people to give up on the regular physical exercise during the maintenance stage, considering the unforeseen barriers and temptations that may occur in the long term. Drawing upon a motivational affordance perspective and the achievement goal theory (AGT), this theory-based manuscript provides design principles for QS 2.0 running platforms, with the purpose to increase users’ physical activity maintenance (PAM). Additionally, we propose a conceptual model explaining the underlying mechanism in terms of how these affordance design principles serve as the sources of two kinds of achievement goals, namely mastery goals and performance goals, which has distinct roles in determining users’ longitudinal exercise performances.