Mentorship, often viewed as a central capacity of leadership, is acknowledged as influential in growing nurse leaders. Mentoring relationships are perceived as empowering connections offering a dynamic guided experience to promote growth and development in personal and professional life. A hermeneutic phenomenological approach informed by Heidegger and Gadamer was used to explore understandings and experiences of mentorship for nurse leadership by 13 Australian nurse leaders. We found that learning and transformation associated with becoming a nurse leader mentor was experienced as (...) an enduring evolutionary process. Participants' life journeys provided experiences that developed their understandings and established their personal identity as a leader and mentor. We considered the journey motif in terms of its inextricable connection with lived time and used Heidegger's ecstasies of temporality as a lens to understand how the temporal dimensions of past, present and future influenced and shaped the development of nurse leader mentors. We found that our temporal existence influences interpretation of ourselves and the world. Individuals can benefit from multiple separate mentoring interludes, with different mentors, over a lifetime. For some nurses, becoming a leader and mentor is a lifelong transformative process that grows from diverse experience and influential role modelling rather than formal instruction. (shrink)