I'm rather new here, and I find this to be a highly interesting thread
I am a native Spanish speaker. I was born and raised in Venezuela. At school we studied some English clandestinely, seeing as our teacher figured it would be useful nowadays. To be frank, if English had been an official course, I probably would have flunked. Past "hi," I couldn't really manage much.
Then the tables turned; my dad was transferred to the USA, and we moved here. I began school here in the fifth grade. Since it's Texas, they have bilingual English-Spanish programs here for limited English speakers. Unfortunately, for reasons I later discovered, my parents decided to put me in full-time English, no bilingual. It was a wreck. I would stay up late doing spelling homework, I would fail all history tests,... you get the idea.

But the suffering lasted only until the fourth month of school, which is when English began to "click." And I'm sure you guys know better than I do about what happens when you're thrown into the ocean to learn to swim, linguistically speaking.
My language ventures were put on hold after my fifth grade year. Sixth grade my English improved exponentially, so I was in honors English by the time I got into the seventh grade. However, seventh grade was when I began studying French. You see, all my life, since about the age of seven, I had wanted to learn Italian. Since they didn't offer it at my school, I decided to take the closest thing-- which I figured was French. Due to my Spanish knowledge, French was a breeze. I kept on studying French for the rest of middle school, and I realized I was very good at it. Then, just last year, I won a huge state French competition as a freshman and received a scholarship to spend three weeks abroad in France during the summer. During this time, my French improved immensely.
This year I am in my fourth year of French (which is a blow-off class for me) and decided to study Latin, simply because there was a hole in my schedule (and I was NOT about to fill it with P.E.... pshh). I figured, "heh, why not?" and signed up for the class. And you would not believe how glad I am I went out on that limb. I have fallen in love with the Latin language and regret not having started it sooner. My Latin teacher has also exposed us to bits of Ancient Greek, and I think it was also love at first sight. I'm definitely planning on learning it at some point.
My friend and I have toyed with Japanese, but I gave up on that rather quickly. I learned the kana, some basic grammar, and around 100 kanji before giving up (stress, AP classes, and other excuses), but I am planning to keep studying at some point in the not-too-distant future and achieving some proficiency and literacy (fluency is not my goal, although I could very easily change my mind about that). My friend, who knows around 2000 kanji by now, will be my inspiration for when I pick Japanese right back up.
I have made some online Brazilian friends, and they have aroused in me an interest in Portuguese. I also have not abandoned my childhood dreams of learning Italian. Although I know I could easily teach myself these languages, I'm hoping to pursue these languages in college as I do my linguistics major, since I want a study concentration that will be interesting, easy, and rewarding. Still, sometimes I can't reach
Aside from that, I find Arabic and Turkish to be beautiful languages that I plan to gain at least some basic knowledge of, at least later in life.
For now, however, my goal is to be able to read Dante in the original Italian; read Vergil, Horace, and Cicero in the original Latin; read Homer and the philosophers in the original Greek; be fluent or near-fluent in Portuguese; understand Hayao Miyazaki movies without subititles; and improve my French skills (maybe read some literature) and have some basic knowledge of Arabic and Turkish.