Teacher change in mathematics education is recognised to be a difficult and at times painful process. This is particularly so in countries such as England where primary mathematics is taught by non-specialist teachers, who have often had negative experiences of their own school mathematics. In this paper we explore primary teachers' emotional relationships with mathematics, in particular what motivates teachers to persevere with professional learning. We examine the case of a primary teacher who developed an identity as a teacher of mathematics. We argue that emotion has both individual and social elements and consider the implications for teacher education. (Contains 8 notes.)