Achieving A TESOL

I have always spoken english but teaching it is another different matter. I understood how to form a sentence but I didn't know why. Looking through the detailed information and usage, it made me realize many things. I used english naturally and I really never thought of how or why. Even for something simple as Simple Past tense, I read it's usage and it reminded me. In a way I feel I've been taking english for granted, not being to explain the true structure and usage. I am not sure if I am making sense to you but I feel I have a better understanding of the language and am able to better explain and teach others.