Flow, the state of deep absorption in intrinsically rewarding activity, is widely recognized for enhancing performance and supporting mental health, yet the neuropsychological mechanisms through which flow promotes well-being remain insufficiently understood, particularly in the context of real-world cultural skill practices. In this study we employed Chinese calligraphy training as a paradigm to examine how flow arises during practice, how it contributes to well-being, and what neuropsychological processes underpin this pathway. Participants completed a four-week calligraphy course alongside a drawing control task. Behaviorally, calligraphy training led to significant improvements in handwriting performance and to increased flow experiences that were specific to the calligraphy task, whereas the control task showed no such changes. Individuals reporting greater flow also demonstrated stronger post-training preference for calligraphy, higher task-related pleasure, and reduced negative affect, highlighting the contribution of flow to emotional well-being. Neuroimaging analyses revealed that calligraphy engaged visual, sensorimotor, attentional, and affective networks, and training enhanced functional integration among these systems, producing a reorganization pattern that distinguished calligraphy from drawing tasks with high accuracy. Regression and predictive modeling indicated that a profile of proficient reconfiguration, characterized by strengthened focal activation together with moderated cross-network coupling, reliably predicted individual differences in flow gains. Mediation analysis further showed that this neural reorganization exerted a significant effect on post-training emotional well-being and that this effect was substantially mediated by flow. Taken together, the findings position flow in culturally meaningful skill practice as a central mechanism for promoting well-being and provide new insights for health psychology and intervention design.