["TESOL Quarterly, EarlyView. ", "\nAbstract\nReflective teaching (RT) is influenced by a range of cognitive, pedagogical, and psycho‐affective factors in second/foreign language (L2) education. However, empirical evidence on the influence of psycho‐affective variables on teachers' reflectivity remains limited. To address this gap, this study examined the serial mediating effects of teaching enjoyment and vitality on the relationship between cognitive flexibility (CF) and RT. It employed sequential explanatory mixed‐methods research design, with a serial mediation analysis used to examine the quantitative phase and to inform the overall interpretation of the study. Using a nested sampling scheme, the researchers, first, invited a total of 312 Chinese EFL teachers to complete four questionnaires. Then, 10 participants from this sample were purposefully selected for semi‐structured interviews. The results of structural equation modeling (SEM) showed significant associations among the four factors. Additionally, enjoyment and vitality worked as significant mediators in the relationship between CF and RT. The qualitative findings obtained by MAXQDA analysis corroborated this interplay, showing that teaching enjoyment and vitality can affect teachers' CF and RT by increasing their “motivation and work engagement,” “openness to diversity,” “resilience,” and “teaching efficacy.” The results highlight the interconnections between reflective teaching and psycho‐affective factors in L2 teacher cognition research.\n"]