Now matter what, you need to consider a few things.
Firstly, it will get better the more you do it. It won't necessarily get easier, but it and you will get better.
Secondly, as my old principal in the U.S. said upon my first year of teaching, "Don't worry. New teachers are typically so bad for the first couple years that they should pay the school district to work there." (And it's kind of true.)
Third, with those two things in mind, just do your best, plan, plan, and plan, and be ready to change and adapt those plans at a moments notice (especially in Korea).
And Lastly, if you're looking for immediate positive feedback, this profession might very well be the last place you should look and that makes it difficult. You may not get a peep out of a student even after trying everything you could think of and 3 or 15 years down the road you may get a visit from them saying how much the things you said or did meant to and or for them, you just don't know.
Teaching is brutally hard because you literally face nothing but critics with very little positive feedback and yet you are supposed to be able to assess not only your performance, but the aptitude, ability, and rate of acquisition of your students.
Do what you can, be as positive as possible, and keep on truckin'. As long as you are self reflecting and doing what you can to get better at what you do, then you very likely are.