In language development, I consider factors such as degree of fluency, the speed of development, and the extent of naturally sounding vocalization. I would classify the above as simply your degree of success, but the definition of success can vary between people, and more to the point, I don’t frame language development in reference to some mark of success.
You could argue that I indulge in semantics. Probably. Yet I want to emphasize how I approach language development. I find it a relatively trivial milestone that takes a bit of time and consistency. I speak of weeks to a few months before you reach a point of automation in the process, and the loop feeds itself (depending if you devote minutes or hours per day). While initially you must take active measures to fill in the context and invest certain concentrated effort, after that given time frame, you can relax and let your consciousness conduct most of the labor.
Why do I not frame the process in terms of success? Because it greatly simplifies achieving it. I take the nature for granted. Tens, or perhaps hundreds of thousands of speakers around the world, acquire multiple languages all the time, with relative ease. If it were a small handful of individuals, five or six perhaps, I could consider it a question of extraordinary talent or notably superior intelligence, although I would still explore the factor to greater detail. With thousands of people, it must be as basic and uncomplicated as any other human feat acquired over a life time. I don’t believe in it. I accept it as an axiom. I know it.
When you wish to effectively acquire some relatively mainstream ability that many have before you, and wish to estimate the degree of the challenge, imagine the bell curve (Gaussian distribution) of that degree across the population. You probably lack the data for the entire population, but you have likely heard of enough cases to form a large enough sample. Within that distribution, mostly everyone contents with either the mean or the numbers within one standard deviation. Don’t settle for that. Mostly everyone in that bulk of the curve feeds off of the feedback and preconceptions of others within the respective bulk, severely overcomplicating the journey and being uninformed of more effective strategies.
Rather, focus on the outliers on the favorable side of the curve closer to two standard deviations out, or about the top 5%. Whatever that group attains, you should take for granted that it’s possible, accessible, practical, and straightforward. It’s straightforward, since in the case of languages, so many have undertaken this before you, that in it lie few secrets. The challenge forms in striving to become the world champion, competing with the top few individuals. In this case, you must prevail over the top percentage, and the strategy takes a notably more unpredictable curve. Otherwise, don’t worry.
Respecting the above in terms of languages, in minding the notion of success, I would be giving shape to the very idea of it being challenging, external to me, and in need of effort, discipline, and perseverance to conquer. But whatever the merits of that thought, I don’t find the thought or the energy devoted to the respect, of any utility in actually conducting the deed. Simply do, as some lesser life form lacking consciousness in it’s own existence. Don’t worry about being extremely naive or of overestimating the challenge carrying low risk. Now, if you’re Napoleon, leading a battalion against Austrian and Russian forces numbering in the tens of thousands, then consider an element of caution. Otherwise, most personal development milestones carry low to infinitesimal risk, with high reward. It behooves you to be aggressive, assertive, naive, nonchalant, or whatever questionable and frowned upon trait you may conceive beyond, of course, evil. It serves as nothing more than means to the end.
Don’t misunderstand me. Something like language development, while entirely natural and straightforward, still demands time, concentration, and consistency. You must still place it among one of the higher priorities. It demands notable brain real estate and a source of energy, so I wouldn’t place it in the spot of your twelfth hobby after evening tea. Otherwise, I would be speaking not several, but a dozen languages.
To summarize. Don’t underestimate. But don’t overemphasize the extent of this milestone. It’s nothing extraordinary, nor mysterious. It’s not beyond your grasp. It’s routine. It’s not worthy of being complimented with a ‘good job’. Imagine Napoleon being told that by his marshals. The idea sounds almost offensive. Alright, I don’t know nearly enough about Napoleon’s inclinations or military campaigns to make that claim. Yet if someone complimented me on the monumental achievement of 30 push-ups, unless in a sour mood, I would silently disregard it as a joke. Rather, take for granted your natural ability to undertake such things and proceed to greater milestones.