Language teacher identity (LTI) has been a significant and growing field of research in English language teaching (ELT) circles for some time, and the increasing pressure on English language teachers working in higher education to develop researcher identities is well acknowledged (Yuan, 2017). However, the importance of language teachers' wellbeing and psychological responses to environmental tensions shaping their professional identities has only recently gained traction in the field and remains an underdeveloped area of investigation. Therefore, this paper reports a longitudinal narrative case study of the researcher identity development of Angelica, an English as a foreign language (EFL) teacher working in the context of higher education in Japan. Using the dual lenses of language teacher identity and Vygotskian sociocultural theory (SCT) -- we traced Angelica's EFL researcher identity development focussing on her growth from a wellbeing perspective. The study revealed that Angelica's researcher identity development was shaped by her perezhivanie -- a key component of SCT, defined as "a unity of emotion and intellect" (Zhang et al., 2022, p.1) -- which in turn was shaped by her mindfulness practices that contributed to her wellbeing. This paper concludes with implications for facilitating the researcher identity development of teachers working in the field of EFL.