Have you ever asked yourself why you are learning English?  It's an important question. Maybe you are studying English to get a better job or for your career.  Perhaps you want to get a higher score on a test. This kind of motivation is called "extrinsic motivation", because the reason you are learning the language is for some other goal, one that is actually not part of the language itself.
The other main kind of motivation is called intrinsic motivation. Some examples of that are studying so that you can communicate with a new culture, or being able understand books and movies in English.  Intrinsic motivation relates to the language or culture itself. It shows a desire to become part of the community of people who speak the language.  It is much more powerful and useful than extrinsic motivation. 
I researched learner motivation for my Master's degree, and most research shows that if you have high intrinsic motivation, it is very helpful to improving your language skill. Most students I meet seem to have higher extrinsic motivation, but really low intrinsic motivation.  Maybe that is why they find studying English boring ? they are only doing it so they can get a higher job or some more money!  I suggest that you try to find some ways to enjoy English, without focusing on a financial or business goal.  Then, you’ll learn it much faster and have a better time doing it. 
One way to improve your intrinsic motivation is to learn about a singer or artist that you admire. If you find some English music that you like, you can study the lyrics and learn new phrases that way.
Another way to increase your motivation is to find a way to interact with English speakers.  Make a friend at one of the western hang outs in Cheongju. Volunteer helping foreigners learn Korean or something like that. The more friends you have who can speak English, the more motivated you will be to learn their language.
Another thing to keep in mind is to be patient. Learning a language is a journey with no end. There are always new phrases and words to learn.  Why not visit this web site with a daily phrase to learn?  That will help keep your motivation up, and you'll learn some fun new words.  http://www.ihbristol.com/learn-online/phrase-of-the-day.php