BACKGROUND: Performance-based financing (PBF) reforms aim to directly influence health worker behavior through changes to institutional arrangements, accountability structures, and financial incentives based on performance. While there is still some debate about whether PBF influences extrinsic or intrinsic motivators, recent research finds that PBF affects both. Against this backdrop, our study presents findings from a process evaluation of a PBF program in Mozambique, exploring the perceived changes to both internal and external drivers of health worker motivation associated with PBF. METHODS: We used a qualitative research design with in-depth, semi-structured interviews with health workers, which included a rank order exercise and focus group discussions. Interviews were analyzed by two researchers using thematic analysis techniques. Rank order frequency was calculated using weighted average methodology. RESULTS: Health workers reported that PBF, overall, positively influenced their motivation by introducing or reinforcing both internal and external motivational drivers. Internal drivers included enhanced self-efficacy driven by goal orientation, healthy competition among colleagues, and job satisfaction. External drivers included an organized work environment, enhanced access to equipment and supplies, financial incentives, teamwork, and regular consultations with verifiers (a type of supervision). PBF stimulates an interactive relationship between internal and external motivational drivers, creating a feedback loop involving responsibility, achievement, and recognition, which increased perceived motivation. CONCLUSIONS: The PBF program helped workers feel that they had well-defined and achievable goals and that they received recognition from verification teams, management committees, and colleagues due to enhanced accountability and governance. Our paper shows that financial incentives could serve as the "driver" to kick-start the feedback loop, of responsibility, achievement, and recognition, in environments that lack other drivers. Understanding how PBF programs can be designed and refined to reinforce this feedback loop could be a powerful tool to further enhance and track positive motivational changes. For countries thinking about PBF, we recommend that policymakers assess the loop in their contexts, identify drivers, determine whether these drivers are sufficient, and consider PBF if they are not. TRIAL REGISTRATION: We obtained ethical approval for the study protocol, data collection instruments, and informed consent forms from the Ethics Review Committee of the Centers for Disease Control and Prevention (CDC) [IRB 2015-190] and the Ethics Review Committee of the Mozambique Ministry of Health.