I have a dream★

In the near future I'd like to speak English fluently and make many foreign friends. Also I want to go on a trip without any language problems. Until quite recently I was afraid of making mistakes in learning English, but Professor Phillip's words encouraged me that we must make mistakes if we want to be good at other languages. Now I'm enjoying this class very much. It's a dream of me to be a doctor in the States one day. So of course, I have to learn a lot of medical knowledge in English but also I think that I need a sense of humor. The sense of humor between Japanese and Americans differ so much that I'm worried whether I can fill the gap. Is there any advice?