I'm pleased to read that learning languages doesn't have to belong only to the young. I have, in my possession, language learning tools on the following languages: Dutch, German, Spanish, Korean and French. I think that's it.
In terms of languages other than English, I was, obviously, first exposed to Spanish. My mom, in her efforts to learn English, didn't speak a lot of Spanish to my sisters and I growing up, though in her accented English, mixed in Spanish words--Spanglish if you will.
(I was relating to a friend recently how my mom used to refer to the Spanish word for radishes. For the longest time I only knew what my mom called it, and looking back on it, it's not even the Spanish word for radishes, but the Spanish word for chopped/sliced (pica). That's how the radishes came, in a package that had them already sliced in small bits that she'd include in salads.)
I took a introduction to foreign language course in eighth grade--origins of language, Latin, German, French and Spanish. After that, I took four years of Spanish in high school, a year of French, and have since taken college courses in Spanish and an independent study class in Dutch. I also spent a week in Spain at age 16, and a summer there a year later. I only wish I could have been immersed in Spanish longer, as I think that's the best background for any language learning.
Combine sincere desire to learn and immersion, and I think most of us are well on our way. Without that, it's a bit more difficult, but not impossible. There's plenty of language classes all around here, and if not that, there's plenty who speak other languages that might be able to help as well. That's not mentioning the books, CDs and other language learning tools available. I picked up almost all of my Dutch books in Leiden, and my Korean books/tapes in Seoul. My Spanish books I picked up here, but then again, I could always practice on my mom, but I'd feel weird doing that.
I actually have enough of an understanding to read at a very basic level, and can communicate well enough to figure out whether I'm eating fish, meat, cheese, or drinking wine, beer, or soda. I think if I could spend a year in Spain, or another Spanish speaking country, I'd get fluent. I think I'd struggle in the beginning, but with a longer period of immersion, I'm confident I could learn. I think it's still possible to learn other languagues besides Spanish--those languages in which I don't have a natural background.
I think I'll shoot for Spanish first, and go from there. I do know a few words in the above-mentioned languages, but I'm a lot closer with Spanish, and the pronunciation comes more intutively for me.