Whenever I am first embarking on a personal endeavor, for example like running long-distance or learning a foreign language, there seems to be a direct, linear correlation between the effort I put into it and the progress I achieve. But it seems like in every case, with everything I do, that effort/results relationship eventually breaks down. With the running I've been doing since 2007, I initially built up my endurance by simply going out there and running longer and longer distances...culminating in running a marathon in January, 2011 while training for the same-distance race later that month. But in the process I injured the IT-band in my leg and my progress was stymied, with me drawing back to running for half-marathons. But even had I not been injured, sooner or later I would have tapered off my training to a state of equilibrium...a maintenance state at the level I was satisfied with. In the years since, I had found that running too much can cause problems with my feet (plantar fasciitis) while my already-sensitive throat, coupled with a tendency for upper-respiratory airborne allergies, can make me prone to coughing over the course of a long run. So just stepping out my door and running down my neighborhood streets for a protracted period of time doesn't bring the same benefits as before...and that detracts from my enjoyment of running...
With the study of foreign languages, living completely immersed in the target language and culture is easily by far the most preferable course. But my life does not lend itself to this, and my learning consists of books, language learning apps like Duolingo and Quizlet, and Internet audio sources. It is possible to develop a good rudimentary vocabulary and get a grasp of grammar...and make great progress with scripts that aren't based on the Latin alphabet...but at a point it all falls short when it comes to understanding a regular conversation or reading an ordinary newspaper or magazine article in that language...
I think one of the problems with jumping into an endeavor enthusiastically and progressing up to the point where we reach a plateau or even a wall is that in many cases we truly do not understand the nature and scope of what we are trying to do. As we get more deeply into the activity we begin to realize its complexities. Take any neophyte president, not just the current one. They all storm into office with their ambitious "hundred days" agendas, making decrees left and right...until the resistance settles in against them, not just from the opposing party but also from those in their own who feel threatened and the need to assert themselves with the new leader. Each president has to finally learn...if they want to be re-elected, that is...that the office they have assumed is a lot more involved and complex than they may have arrogantly assumed when they were campaigning for it...
It seems like with any worthwhile long-term endeavor, clarity is the rule at the beginning...but chaos eventually takes over with all-sorts of conflicts and complications. Gee, I don't mean to sound pessimistic, but that's just how I see it...