I believe that there is a spectrum to the motivations of teachers.
On one side, there are the teachers who just really love to teach; the subject they teach is secondary to the pure joy of helping and watching people learn. The younger the students you teach, the more likely you are to be this type of teacher. These students need to be lead to the learning; its still something they “have” to do, and not something they “want” to do.
At the other end, is the teacher who really loves their subject; teaching is just a side gig that at best, they also really love to do, and at worst, they only do because they have to in order to keep their funding or residency. The older the students are, the more likely they are to have this sort of teacher. These students already should love their subject and have actively sought out their learning opportunities. That makes up for any disinterest that the teacher may have.
In the middle is where I want to teach. I love my subject and I love helping people learn, and I will always strive to become better at both. I want to be the teacher that helps her students come to the discovery that they actually like learning; that they are interested in something and can be self-motivated.
I think that I was very lucky that all throughout high school I had many teachers like this. They push you to be better than you thought you could be. They somehow got a bunch of teenagers to respect them enough to want to hand in their best possible work; not for a grade, but to see their teachers triumphant grin. That in turn leads to the student doing their best just to feel accomplished in themselves.
That, in my humble opinion, is the most significant lesson a teacher can convey; that students can be their own teachers.