What am I supposed to do with this Vietnamese language in my head?
I worked hard to learn Vietnamese. I never got as good as I wanted to get, but I got pretty good. My wife and I were at the Foreign Service Institute for almost a year, most of that time in Vietnamese class. For five hours a day we were in small-group classes. Then, hours of homework and self-study after that. I didn’t have to take it quite as seriously. But I’m an overachiever. I filled up four (FOUR!) notebooks with vocabulary words. I made dozens of flash card stacks with Quizlet (highly recommended for language learning, BTW). I did my best.
After arriving at post, I continued to study, four hours a week with a private tutor (thank you, Post Language Program!  Xin chà o Cô Tươi!). She patiently endured my over-analyzing her language, poor her.
I tested again in March, late in the evening over the Department’s video conference system (after getting an MRI that morning, but that’s a different story). Again, I didn’t score as high as I wanted, but I improved.
I asked the local staff in the office to help me practice Vietnamese. They were good sports, including me in their banter (the Vietnamese people are very good at banter, by the way). I followed most of it, and it got easier as I practiced.
I invested a lot of sweat and effort in learning the language. I read several books, hundreds of newspaper articles, struggled though countless hours of television (television news in Vietnamese is really, really hard). I started talking to myself in Vietnamese, dreamed in Vietnamese, even accidentally used Vietnamese instead of Chinese with my wife. The language finally got a firm foothold in my brain. But now that my tour is over and I’ve left Vietnam, what am I supposed to do with this language?
Of course, we can try to go back to Vietnam for another tour of duty.  My wife and I have talked about it, and we both agree that another tour in Vietnam would be great.  Hanoi would be an interesting place to live and work.  So that would give me another chance to use Vietnamese professionally.  But that is at least two years in the future.  In the meantime, I have this head full of Vietnamese, some of it correct and accurate.  It might fade in two years, but it’s so firmly entrenched in my brain now that it won’t go away.
It’s a different situation from Chinese. Not being in a Chinese-speaking work environment isn’t weird for me.  I’ve been a Chinese speaker for more than half my life, and it’s our home language.  But I only spoke Vietnamese in the office and on the street.  Now that I’m out of a Vietnamese environment, I feel like I’m neglecting my language proficiency. I don’t regret the investment that it took to learn Vietnamese. But not using it anymore seems like a waste.
Don’t be me wrong, I’m not complaining. I’m grateful for the opportunity to learn another language. It’s just a little frustrating that I won’t be able to use it professionally for several years. After putting so much work into learning, I don’t want it to fade away.