How long does it really take to learn a language?

I have become more and more interested in learning languages since moving to Europe. I studied German (hopelessly) in high school, and studied Japanese in college, but since moving to Germany over three years ago I have come to truly enjoy it. I have gotten to an upper-intermediate level in German mostly via self-study and immersion, and have started learning Croatian since it's the native tongue of my girlfriend. With an upcoming move to Paris and therefore French learning on the horizon I'm actually motivated rather than intimidated.

Along my journey of getting interested in languages I have many times clicked on fluentin3months.com, where Benny The Irish Polyglot (and now a team of bloggers) talk about the fun of language learning. His philosophy, outlined in his language hacking guides, is that book learning is over-rated and the best tactic is to speak from day one. He is absolutely right, and has proven it during many of his language challenges where he travels to a location and attempts to get to a certain level in his first 3 months there. What I have learned however is that book learning is very useful and important, but passion (and the hard work and determination that comes with it) is even more directly important. Book learning often drains passion, so it is only indirectly over-rated.

Is it really possible to become fluent in 3 months? Probably yes, but not for everyone with every language, and it's definitely not easy. But that's not the point of Benny's site anyway. The point is that setting goals and not being afraid to speak are necessary to make real progress.