Prospective and practicing elementary teachers have historically demonstrated anxiety about mathematics, which can affect their mathematics teaching and their students' math anxiety. Yet, developing productive dispositions prior to teacher preparation programs is rarely addressed in the research. We propose mindset messaging in mathematics courses as an intervention to influence prospective teachers' (PSTs') self-reported mathematical mindsets and math anxiety. Survey results indicated shifts toward growth mindsets and decreases in math anxiety. Further analysis of PSTs' written responses suggests that mindset messaging may support PSTs in overcoming math anxiety, and that perseverance during problem solving is critical for PSTs' mathematical improvement. Additionally, some PSTs connected course experiences to future mathematics teaching practices. Results propose MTEs might consider explicitly offering mindset messaging in mathematics courses.