When I was 19, I accepted an internship in a country where I didn't speak a word of the local language beyond "zdravo!"

The experience of having to learn a language on the fly (and living in mortal fear of answering the phone) profoundly impacted me. When I returned to the U.S., I began teaching English as a volunteer. Based on my own experiences abroad, I first taught a workshop for speaking on the telephone, and quickly moved on to provide individual tutoring.

I have since learned a numb...