I heard that if you can heal yourself, then you can become a great teacher.
This can take years I think, not just days.
I also think that when you are great, you don't want anything from your students. You are just like the sun and the rain, giving without expecting. Teaching really is (or can be) *karma yoga.
*from wikipedia "Karma Yoga is described as a way of acting, thinking and willing by which one orients oneself toward realization by acting in accordance with one's duty (dharma) without consideration of personal self-centered desires, likes or dislikes. Acting without being attached to the fruits of one's deeds."