Lydia Machova, an interpreter (and polyglot) who did a bunch of interviews with polyglots about how and whey they learn, summarized her research with this: “we aren’t geniuses... the one thing we all have in common is that we [find] ways to enjoy the language learning process... all of us use different methods, but we make sure it’s something we personally enjoy.”
Anthony Lauder, author of the Fluent Czech website from way back to when, said something similar — that the key is to simply love the learning process. “[To study in such a way that] studying isn’t a chore, merely a task to get out of the way so that you can reach the fluency that you list for — no. List fizzles. But if you love the language, if you love the language learning process—those hours, those minutes and those years—they’ll fly by, and it’ll feel like minutes. And that’s the way to fluency; to fall in love with the process... and then to do what you love, for hours and hours a day, for years and years, but for it to feel like minutes.”
Language is a huge, incredibly broad thing; not something that can be shoehorned into a semester or one-size-fits-all magic trick. It’s important to find a way of learning that addresses the things you personally feel are important in life.