Although language teacher well-being has been the focus of growing attention in recent years, there is little known of its dynamic and contextually dependent nature. Integrating the complex dynamic view of well-being with an ecological orientation, this classroom-based study examined the micro-scale changes in pre-service language teacher well-being and the reasons for such changes using data from three pre-service English-as-a-foreign-language (EFL) teachers in Türkiye. The individual trajectories of well-being were tracked in a particular class over 4 weeks through self-ratings of well-being at 10-minute intervals during the lectures, journal entries, interviews, and stimulated recall sessions on individual microteachings. The findings suggest that the experience of pre-service language teacher well-being in the classroom ecology remains subject to inter and intraindividual variability over time, displaying nonlinear trajectories not only within sequences of single lessons but also from one lesson to another in response to a host of personal and contextual factors. These findings imply that pre-service language teacher well-being is not static, but instead is enhanced and reduced at particular moments in the classroom as a result of the interplay of a myriad of variables. We end with a call for more research into micro-scale changes in teacher well-being within applied linguistics and beyond.