Teacher enthusiasm is a key factor of effective teaching, favouring teachers’ well-being and instructional behaviour, and students’ cognitive, emotional, and motivational outcomes. Research has largely examined its positive effects, while neglecting the interplay of factors shaping teacher enthusiasm. This study aimed at examining the interrelations of motivational (teacher self-efficacy), affective (positive emotions), and well-being factors (job satisfaction) in shaping teachers’ experienced enthusiasm. A sample of 536 high school teachers participated in a follow-up study with a time lag of approximately six months. Results confirmed that positive affect was related to enthusiasm both directly and indirectly via self-efficacy and job satisfaction. •Teacher enthusiasm (TE) is a key factor of effective teaching.•This study examined the interplay of three teachers’ personal factors favouring TE.•Positive affect (PA), self-efficacy, job satisfaction related over time and with TE.•PA related with TE directly and indirectly via self-efficacy and job satisfaction.