Past experiences as mathematics learners play a critical role in the way mathematics teachers consider what it means to know, do, and teach mathematics. Thus, under-standing past experiences and ways to work with them in teacher education is a critical concern. Using phenomenological inquiry, we investigated moments of shift that occur along one's mathematics journey. The study draws on 30 prospective teachers' experiences in the form of lived-experience writing and interview data. Findings show that prospective teachers' shifts manifest in relations with others, across different time frames, and through material relations with mathematics. Most salient was the tentative and mutable nature of shifts, showing that shift might be better viewed as a possibility rather than a single event.