My truthful answer is not very inspiring. I enjoyed languages at school and university, and then drifted into teaching because I couldn't think of anything else to do. A PGCE teaching qualification seemed the passport to a safe career if ever I decided to settle down, and TEFL gave me the chance to travel at no cost.
It was only after I had been teaching for some time that I discovered that I found it personally satisfying to help people learn something that I found enjoyable. I did briefly leave teaching a couple of times, but soon returned.