I've switched most of my language preferences to french. Like facebook, gmail, any site where I can set a language. Just so I'm forced to deal with the language sometimes. When you're writing in another language, switch the spellcheck options to the language. But it's an active process, you have to read, write, speak often. Find some people who speak french and try and tell someone a story, your grammar will be awful but it will force you to explain something in the words you do know. Learn the little phrases like, "What's the word for?", "I don't understand, could you please repeat" in french so that you can use them in conversation. It shows your willing to learn and people will take their time with you.