This study explores how lived experiences contribute to pre-service and novice teachers' redefinition of prior professional and academic identities in developing a mathematics teacher identity. It focuses on participants preparing to teach or teaching students aged 13-18. A hermeneutic-existential phenomenology perspective compares participants' lived experiences in and after short-track teacher education. The data were collected through semi-structured interviews with four pre-service mathematics teachers and four novice mathematics teachers and subjected to a thematic analysis. Findings show that the participants encounter turning points conflicting with their lived experiences, which fosters reflective awareness. Redefining identities occurs as the participants navigate these turning points, resulting in a balanced development of a mathematics teacher's identity, where new aspects can emerge, or established ones can dominate. The participants express that teaching mathematics is about sharing joy and meaning. However, given the persistent struggle to balance student needs with professional demands, they question this vision in practice. Novice teachers, often feel frustrated compared to pre-service teachers when they are unable to meet their students' needs and contemplate teaching at higher levels. Questions arise about how short-track programs can prepare pre-service mathematics teachers to develop confident identities to prepare them for the teaching profession.