How did you become fluent in another language?

I want to be fluent in another language. Right now, I'm thinking German. But, there are a bunch of other languages I'm interested in. I know there are a lot of different products and ways to learn a language (classes, software like Rosettastone, Pimsleur, etc..., going to the country that speaks the language) What I want to know is how you became fluent in another language. What tools did you use? How long did it take you? Does that make sense?