Motivation and necessity are keys to learning a language. I am presently in Korea, teaching at a College, and I have noticed that the foreign low skill laborers from countries like Uzbekistan, Kyrgystan and Pakistan learn surprisingly good Korean in a relatively short time (6 months to 1 year), because they need to communicate with their bosses who do not speak English, and because they are in an environment in which only Korean is spoken (the low skill Korean jobs).
Mormon missionaries are another example of foreigners to a country who learn/acquire a language at record speed. The key to their success is the 2-3 month total immersion in Utah, where they learn and speak the new foreign language 8-12 hours a day, and then when they go to the new foreign country they hit the streets and speak the language basically all day on their mission - that is much more effective than sitting in a classroom.
Classroom learning will only give you the base in the language. After than you need to go out and practice the language.
I work with languages and learning languages is a hobby to me (fluent in French, German, Spanish, Italian, Portuguese, and conversational Mandarin, Turkish, Tagalog).
I am presently learning Korean, and this is a real challenge, but all languages are doable.
Don't believe people who say that it is super difficult to learn a language as an adult. Motivation and the chance for practice are keys to gradual learning.
You can even do it in your own country, with classes, cd's, and medium. Start with really low level, and move up gradually.
Just investing in a 2-4 week total immersion in the country of your choice can pay huge dividends. You can do this during your vacation time.
Most teachers in Korea start learning Korean with good intentions, but attrition rates are very high, because so many are discouraged by slow progress. But, if you stick with it, and gradually improve your knowledge of the language with comprehensible input which is relevant to your life, improvement will come as a matter of course.
Finally - some languages you can pick up by living in the country through a process similar to osmosis. For example French, German, Spanish, Italian and Germanic languages would fall into those categories. All those languages possess so many cognates that comprehension is much more readily acquired.
With other languages which do not belong to similar linguistic families, including most, but not all, Asian languages - you have to deliberately study the language to make any headway...
Ghost in Korea