It's fairly often enough that questions pop up asking about language learning. Usually the questions ask how useful it is to study a language, and which language one should study. If you go about it with the goal of fluency, then it is definitely useful, and will definitely pay off.
I've found that there are 5 big things you need to do to develop all-around (reading/writing/speaking/listening) fluency in a language. And if you are going to take the time to learn a language, your goal should be fluency if you hope to someday use the language in a business context. Nobody has any use for a kid who can only utter a few disconnected phrases.
To become fluent, you need to immerse yourself in the language. What does immersion mean? For starters, immersion definitely entails living in the country where the language is spoken. However, living in the country in and of itself will not immerse you. It's entirely possible to live in a country for years and never speak the local language beyond "hi/bye" and giving basic directions to a taxi driver.