You basically have to train yourself to think in a completely different way. It goes against everything you’ve ever been taught about communication. You have to learn this in a relatively short period of time, and it’s not second nature because, chances are, all of your friends and family speak English.
Well, if you want what you learn in your foreign language class to stick longer than your next quiz, you have to dive into the language, so to speak (pun intended).
In order for the language to become more second nature, think of yourself as a child learning how to communicate. You have to learn a language by association, by ear, and by conversation.
Train your ear by hearing the language. Listen to music in that language. Play your favorite movies dubbed in the language. You already know what happens and what’s being said, meaning you won’t be lost. This will adapt your ear to hearing the language in a natural way.
Converse in the language as much as you can. Get with someone in your foreign language class and talk to each other in that language. In time, words will roll off your tongue.