Learning a language
Learning a language can be compared to building muscle in exercise. After months or years of hard work, the so-called "Tipping-point", we finally come to recognize the progress and to maintain it, we still have to make as much follow-up effort as we have had or more than that in terms of time and energy.
The input-process should work with the output-process to make the most of the productivity. Otherwise, we could be overly confident or overestimate ourselves. Without the right feedback, the expected results are never promising.