Self-reported job satisfaction in K-12 teachers has decreased and it at its lowest in over twenty years. This study explored mindfulness levels—acute attentiveness and awareness of self-judgment and judgment on others—and teacher self-efficacy (TSE) levels-- how well teachers felt they perform teaching tasks—in student engagement, instructional strategies, and classroom management. The construct mindfulness and its subfactors were specifically measured for teachers’ attentiveness, teachers’ attitudes and willingness to forgive their weaknesses, their personal perceptions of how they act with awareness, and their perceptions of their own nonjudgmental attitudes. Three mindfulness scales measured teachers’ perceived acute self-awareness, and one teacher self-efficacy scale measured levels of teacher self-efficacy (TSE). Three models using multiple linear regression analyzed three different types of teacher efficacy: student engagement, instructional strategies, and classroom management. Results indicated a significant difference between TSE for student engagement for male teachers and how observant these teachers were of how their students were engaged in the classroom. Female teachers showed a slight increase but not significantly in TSE for student engagement in relation to how they observed their students’ engagement. A negative correlation was found between determiners age and attitude or how a teacher pays attention to their making of critical judgments or their being non-judgmental. In addition, TSE for instructional strategies and mindfulness factors describing, attention, and attention awareness positively correlated. Interaction of years of experience and acting with awareness also revealed a strong positive relationship but gradually weakened as teachers’ years of experience increased. After ten years of teaching, the relationship between TSE with instructional strategies became non-significant with teachers’ sensitive awareness of their present situations. Both factors years of experience and job satisfaction significantly predicted participants’ TSE with classroom management. Nearly retired teachers had lower efficacy in student engagement and instructional strategies, possibly indicating that near-retirement teachers are becoming mentally tired from years of hard work and are not actively engaged in professional development. Furthermore, these teachers feel less confident in how they are performing in the classroom.