I am a laughably bad runner. Absolutely terrible in fact. Because of this, I keep running.
I’m training for my first half marathon now (time goal: finish same day I start) so Monday I ran the longest I ever have in my life so far – 15km. Today, two days later, calves still sore, I did 5km in the fastest time I’ve clocked in several months.
When learning Japanese, the time it takes to comprehend things is one of the biggest sources of frustration there is. Even once you can get through a short story or a manga chapter in reasonable time, it might take months before some of the details snap into focus and you finally understand the points that were beyond you the first time.
But the mind and the body are built much the same. If you want to run fast, you have to put in a lot of distance. If you want to read fast, fully understand fast spoken dialogue, speak without hesitation – you have to plod through characters in the tens of thousands at whatever pace you can manage, listen to days and weeks and months of audio, and practice conversing until even the fencepost gets tired of you. And if you do that, the fluency will come, the speed will come, that feeling of effortlessly flying along with your favourite author will come.
Physical or mental, there’s no shortcut, but the proven path is well proven, if you will only stick with it long enough.