My native language being German, I've learned Russian and French at school (even after so many years, there's a little left), taught myself English, Polish and Hungarian, and at some point in time even tried to learn Vietnamese, but it foundered for the lack of listening possibilities - did you know that many of these South-East-Asian languages have different speech melodies, that is the same word has completely different meanings depending on the intonation? And I tried to learn it in olden times, before the epiphany of the internet.
I would like to learn Hungarian anew (when you don't use a language you quickly forget the most of it, but the "feeling" for it remains), but judging by my recent attempt to learn Finnish, it's probably not going to happen in this life. I just don't feel like using my brain this way anymore.
Although ... what I would really love to learn is Irish and Welsh! And I would if I could find a good teacher/course book/programme ... any tips?