Background: Passion is highly prized. The Dualistic Model of Passion provides a general roadmap for how people develop passion, at least under conditions in which they can freely schedule their daily activity, abandon activities they no longer value, and have flexible time to invest as they see fit. But teaching is a different, because many aspects of this activity are fixed and pre-set by circumstances. Recognizing this unique condition of classroom PE teaching, we designed the present investigation to test the merits of two antecedents teachers can utilize to develop greater (harmonious) passion--namely, participate in an autonomy-supportive teaching workshop (Study 1) and incorporate intrinsic instructional goals into their lesson plans (Study 2). Purpose: The over-arching purpose was to investigate the potential of two malleable and personally controllable catalysts to greater harmonious teaching passion. Method: Study 1 used a randomized control trial. We randomly assigned 104 Korean PE teachers to participate (or not) in an autonomy-supportive teaching (AST) workshop. PE teachers self-reported their harmonious and obsessive passion at the beginning, middle, and end of an academic year. Study 2 used a longitudinal research design and a sample that included both PE and non-PE teachers. These 134 secondary-grade level teachers self-reported their intrinsic instructional goals, autonomy-supportive teaching, and harmonious and obsessive passion across three waves. Results: In Study 1, a repeated-measures ANCOVA showed that teachers in the experimental condition, compared to teachers in the control condition, showed a longitudinal increase in autonomy-supportive teaching and harmonious passion and a longitudinal decrease in obsessive passion. A mediation analysis confirmed that participants in the AST workshop experienced greater autonomy-supportive teaching that then explained their greater harmonious passion and lesser obsessive passion. In Study 2, a structural equation modeling analysis showed that adopting intrinsic instructional goals early in the year longitudinally increased harmonious passion (but did not decrease obsessive passion). A mediation analysis confirmed that teachers who more adopted intrinsic instructional goals experienced greater autonomy-supportive teaching that then explained their greater harmonious passion. Conclusion: Teachers can gain personal control over their harmonious passion. They can do this through greater autonomy-supportive teaching. And teachers can become more autonomy supportive in two ways: Participate in an expert-provided professional development experience (Study 1) or incorporate intrinsic instructional goals into the delivery of their instruction (Study 2). Additional ways teachers can develop harmonious passion may be possible, so we encourage future research to continue this search with additional samples, such as sport coaches.