This exactly. My favorite teachers throughout every level of education were first and foremost passionate about whatever it was they were teaching.

I had an absolute goober of a football coach as a teacher for an earth-science/physical science (blanking on what it was actually called) class in middle school. Coaches were required to be teachers, and every coach me or my friends had up till then was boring, even though they knew the material well, being middle-school level amd all.

But my science class that year was my favorite class I'd ever taken in school. Even though I'd already learned most of the material outside of school, I paid attention every single class because coach was genuinely interested in the topic, and you could tell. I remember when we had a unit over the geology and makeup of the earth, he was literally giddy the day we started it because he was planning on showing us the movie The Core at the end of the unit.

This underpaid coach and teacher had actually found the time to fight for a movie not approved for use, despite having a list of plenty of other media he could've shown. I remember that really impressing me too. You could tell he was excited about the lessons, and I can't remember a single student who wasn't interested in class discussions at some point.

Be interested, and genuine.