My best teacher or mentor:

Was a dynamic speaker.

Studies have shown that dynamic speakers are well-liked (it's called the halo effect) - but unfortunately it does not guarantee learning. Eventually, a student who isn't learning will get frustrated and upset - losing motivation. Dynamic speakers can get students motivated only so much. Eventually reality sets in and the student realizes that he or she may not really have the skills needed to do the job.

Try another choice:

Presented information very clearly.
Created an environment where I wanted to learn.