I found that answers are harder to provide, especially when it comes to your own native language. With English, I have been speaking it my entire life, but I know that there are few incorrect grammar points that I unintentionally throw out while talking. When I have to explain a nuance between words, I have to think long and hard for examples to make it easier to understand. With Japanese on the otherhand, I studied in a class from the beginning. Since my teachers explained the grammar points, I know exactly how to explain any grammar point I learned from class.