I've never shared in any of these things on this forum, but it was so nice reading everyone's replies and stories, so I thought I'd add my own.
I grew up speaking both English and French, generally French with my father and English with my mother, and attending French school (albeit sometimes in English-speaking countries) until I graduated high school.
I lived in both Haiti and the Dominican republic for 4-5 years growing up as well, where I picked up my Haitian Creole and the beginnings of my Spanish. In this case, it was a little more of a choice for these languages, in the sense that I actively chose to speak Kreyol to friends at school in Haiti, and I remember really wanting to learn to speak Spanish as well. I continued Spanish through to college, mainly through classes and some limited interactions with people in the city in which I lived and while travelling.
Korean was my big choice. I remember registering an account on HTLAL when I was a freshman in college, so about 10 years ago now, and creating a thread asking if I should do a beginner's level immersion in Korean through a government scholarship I had gotten, or pass on that to go study Spanish. Someone, I forget who, made a compelling case for Korean, and I made my decision based off that. So the next 5-7 years were really focused on Korean, and I got rather good at it, met my future wife in college and never looked back
Japanese came through Korean, being in touch with other Korean learners, the majority Japanese. I learned to a fairly passable level, equivalent of about N2, but then dropped off in around 2015 when I decided to focus a lot more on work, and grad school applications and everything...
Chinese, I chose to learn after visiting a small village in central Darfur, in Sudan, for work, and seeing that there were some Chinese people there. Granted they were not speaking in Mandarin, but it was enough to make me really feel the usefulness of Chinese and to want to learn all the more (I had previously just flirted with the language).
Italian, these days, is due to work--while not required for my work, the organization I work for is headquartered in Rome, and I lived there for a year previously, just using my Spanish to get by. I have a lot of Italian colleagues and the more I hear the language, the more I like it. Also, candidly, it's much much much easier for me than Chinese, and it feels good to be able to talk to people from Day 0, to be able to start reading novels, to watch shows and understand so much, right off the bat.