Let's clear up a common a misconception. If you properly learn a language you will not (cannot!) forget it. You might get a little rusty and forget a few less common words, but you will not lose the ability to speak that language. Anyone who tells you otherwise has memorized words and phrases, but has not truly allowed that language to become a part of them.
So what do we mean by properly learning a language? Learning the grammar, the vocabulary, idiomatic usage, and... the culture. Learning a language means that you also learn a culture. Luckily for you, this means that you'll get to watch some films and listen to some songs. That's not so bad is it? How about food? Yep, you'll need to try some new recipes (or find a new restaurant). You've got to get in there and allow this new culture to become less foreign.
exercise #1: Try to find a DVD spoken in your chosen language. Set it to speak in the original voices and simply put the subtitles on English. Start to listen to the rhythm of the words and phrases. At first it will seem like a high-speed jumble, but eventually it will start to seem more natural.
Enjoy the film. How did the film differ from an American film?
exercise #2: Find the word for "bread" in your new language. From now on, that is your only word for bread. Your friends and family will get used to hearing you say it. Don't worry. Start using this word exclusively. Even if all of the other words you say are still in English, it will help your brain to associate the concept of bread to this new word. Words are only labels, after all. Attach a new label to the underlying concept of 'bread'.
Do the same thing for "milk" and "water". These are good words because the occur frequently in daily life.
exercise #3: Eat a meal at a restaurant which specializes in your target country's cuisine. If this is impractical for where you live, download a recipe. Enjoy the meal. Did you like the food? Do you think that people who live there eat that kind of meal of every day?
exercise #4: Find some songs from your target country. Order an album or purchase some tracks online. Enjoy the music.
The point of all of these exercises is to make the foreign culture seem less foreign. The words themselves will make more sense when you understand the people who speak them. Besides, a new perspective is never a bad thing. In my experience, every culture has some things that they do particularly well. Find those things. Allow the strengths from this new culture strengthen your own life. You never when something that you try for a few weeks while learning language might become a permanent part of your life.