Objectives Research concerned with mindfulness-based program (MBP) teacher training has focused on the importance of developing teacher competency and integrity, with little emphasis on the experience of trainees themselves. The aim of this study was to investigate the experiences of trainee MBPs teachers as they delivered their first MBPs, with a focus on how they utilized their personal mindfulness practice to support themselves during this time. Methods We explored the experiences of university-based trainee teachers of Mindfulness-Based Stress Reduction (MBSR) when starting to teach, the ways they negotiated any challenges, and the extent to which they felt supported by their mindfulness practice. Semi-structured interviews were conducted with new MBSR teachers currently on a training course (N = 8). The interview data were analyzed using inductive thematic analysis. Results The key findings of the study were that trainee teachers were deeply motivated to teach MBPs with great integrity; did not anticipate the amount of time and effort needed to deliver their first MBSR courses; had concerns about the viability of the 8-week format of MBSR; needed more development in the area of self-reflection; and do indeed practice what they teach, and used their personal mindfulness practice to work with challenges. Conclusions These findings show that trainee mindfulness teachers are actively engaged with developing their teaching skills, and offer directions for how the pedagogy of MBP teacher training may be further developed. Trainees might benefit from additional pedagogical input on the practicalities of delivering MBSR in community settings, and on the development of reflective skills.