I always got the impression that English was fairly easy to learn, because it’s so international and accessible. But, it’s actually a lot more difficult than I realized having helped people here. They often ask grammar questions that I can‘t answer because I’m a native US English speaker and never studied the grammar. We did in school, but most people never paid all that much attention to it and kept on speaking the way that was natural to them.  So, we kind of have to go off of what sounds right and what sounds wrong to us, and I know that’s no help to English learners. Native speakers never „learn“ their first language, they acquire it. Just like you never learn how to see.  It grows in their head. Learners of a second language go through a much different process when learning their second language. 

You may want to go back to what got you started learning English in the first place and see if you can recapture some of whatever motivated you in the first place. If you can find that again, maybe your motivation will return.