A lot of people will give you a lot of different ideas for this. I am sorry, but I will give you the advice that I think you need. Suck it up. Even if you don’t enjoy it, suck it up.
If you are a native English speaker, you probably know quite a bit of very obscure English simply through exposure here and there throughout your life. The problem with assuming that the same will happen in Japanese is that you don’t have a lifetime. If you are specifically studying for a test, read the type of documents that contain that particular grammar frequently, even if it’s not your thing.
I was always a terrible student, didn’t achieve anything at school, then when I was about 19, my coach (gymnastics coach) of all people gave me the best advice I have ever received. He used to frequently tell me that I needed to get better, wasn’t good enough, etc, etc. I was weak, not improving, not becoming a better athlete, and he said to me. ‘Kidd, (cause my first name was hard to pronounce for him). Kidd, look… The more shit you put on a plant, the more it grow.’
After that I suddenly had a realization that my shortcomings were because I couldn’t just get under the damn barbell for 20 minutes without complaining like a spoiled child. Some things you need to earn through sweat and effort.
Sorry, this definitely isn’t the advice you were after. But remember that every second you are reading in Japanese is an improvement. I recommend the app ‘smartnews’. As it is for Japanese people and does not pull any punches in terms of grammar/language.