Hermeneutic phenomenology, which is commonly actuated in empirical research, presents many difficult challenges to investigators aiming to defend the credibility of their research. In particular, the phenomenology of lived experience reveals thorny issues of the relationship between lived experience, awareness of an experience, and describing or explicating the experience. This Methods in Action case reports on the research design challenges faced in a PhD study exploring the lived experience of nurses who mentored students in their workplace. It discusses the methods employed to capture and analyse information about the lived experiences of participants within a diary-interview design. At all stages, it refers to theoretical and philosophical viewpoints, explaining how they guided the study and supported a claim for research credibility. Given that hermeneutic phenomenology involves ‘humans studying humans’, the case discusses the role of reflexivity in the process. Given the personal commitments demanded of participants, the ethical considerations are also discussed. It aims to encourage readers to explore or pilot the use of diary and interview combinations.