It is too hard to speak English what I want to say. After some lab course,I exhaust myself gauging my English. I think, gauging is not good of me. But I couldn't stop. Sometimes, I talk to myself, "Please, be patient. You are not native speaker. Just keep going. Don't gauge yourself." These talks give me a little help to overcome the depression.
I found the most useful paragraph, written by Calvin Coolidge, to overcome it.
"Nothing in the world can take the place of persistence. Talent will not;nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated failures. Persistence and determination alone are omnipotent."