PurposeAs fitness apps have integrated gamification elements into their design to transform exercise into a compelling and competitive experience, this study draws on the expectation confirmation model (ECM) and self-determination theory (SDT) to propose a comprehensive framework for sustained usage by satisfying the psychological needs of users.Design/methodology/approachA longitudinal study design is utilized where data from 598 fitness app users were gathered over two distinct phases separated by 24 weeks, where data were analyzed using structural equation modeling.FindingsThe findings until phase 1 depict that motivational affordances significantly affect mastery, autonomy and relatedness, which in turn exert a significant influence on flow. Identification and compliance have a more pronounced effect in phase 2 compared to stage 1 of the analysis.Research limitations/implicationsIndividuals are more prone to being swayed by fellow members of their social group who share an affiliation with fitness apps, leading them to sustain their usage of fitness apps. These insights can potentially guide app developers and marketers in formulating strategies based on modifiable factors to foster sustained growth for gamified fitness apps.Originality/valueThis study takes a novel stance by employing social impact theory (SIT) in a longitudinal setting to reveal how users react to identification and compliance effects during initial and post-adoption usage of gamified fitness apps.