The present study examined whether secondary school (SE) teachers (N = 324, M[subscript age] = 37.97) and university (UNI) teachers (N = 225, M[subscript age] = 44.80) with a firmly grounded and well-explored teaching identity would report better work-related well-being and would adopt a more motivating teaching style. We expected the opposite for teachers ruminating about their teaching role and also considered the mediating role of teaching motivation. Results from multiple group analyses confirmed the hypotheses, showing that teachers with a well-defined teaching identity reported more satisfaction and less emotional exhaustion during teaching and were less likely to leave the profession. They also reported making use of a more motivating teaching style, characterized by more autonomy support and structure, and less control and chaos. Conversely, teachers who ruminated about their teaching role generally showed opposite correlations. Teaching motivation mediated at least partially these associations, with the results generally holding across SE and UNI teachers. Overall, the present study underscores the importance of considering teachers' sense of identity and teaching motivation as they might underlie their well-being and motivating teaching style in the classroom.