What is one word answer for "the person from whom we learn to be diciplined?"
Many types of people fill the role and the first for most people should be their parents. However, all such people are Disciplinarians of some sort because that's the essential definition of the word.
The linked Dictionary is The American Dictionary of the English Language, which was written by Noah Webster & published in 1828.
disciplined has the meaning of
Showing a controlled form of behaviour or way of working
And I can't find anything more appropriate to teach at the same time behaviour and way of working than the one we call master.
- an owner of a slave or animal
- a person very skilled or famous in a discipline, as an art or science:
one of the great masters of modern art; a Zen master.
The owner part enphasis the disciplined behaviour you have to learn.
It is an alternative to the common one : teacher.