Ohh, another analogy!

Learning a second language to a native level is like losing weight. It requires a long term sustained effort which is unbelievably easy to quit. How many people do you know who have lost weight only to gain it back? Maybe they lose it, it comes back, they lose it again, it comes back etc, but it never stays off. It's just like learning a language. From day one you can't stop, ever, or you start all over again.