This question will probably be moved to the discussion group for teachers; certainly, it will serve you better there.
For many teachers, the reason that they have entered the profession lies in their own experiences in school. Usually, they have been inspired by one teacher, especially. This is a teacher who loved his/her profession, and who also touched the individual and in such a way that the student wished to emulate his/her instructor. Added to this inspiration, the individual who has felt called to teach, has a certain heart within him/herself that makes the person feel there is something worthwhile which he/her can give to others. Perhaps, it is this yearning to give to others that inspires people the most to become teachers.