A very interesting thread. Makes one look deeper into oneself and think...
I've had a latent interest in Japan and all things Japanese for a long time, it must have started about 13 years ago with a Japanese textbook my mother presented to me for some reason. I have worked through it at the time and achieved a basic understanding of how the language works and - surprisingly! - some ability to read (or rather, succesfully decipher) Japanese literature. Then other interests took priority... I would come back to Japanese once every 3-4 years and play around with it for a bit without getting too serious. Gradually, a deep interest in Japan started to develop. I had a vague idea that I might want to live and work in the country for a few years, just to try it out. But then, at some point of time, I realised that 'playing around' would not get me anywhere and actually gave up on the language study altogether for a number of years.
Then came a point when I realised that life goes on and if I am still serious about ever living in Japan, I might as well check it out: if I hate the country, it'll be a closed chapter. If I like it, I'd better start working on properly learning the language and getting myself over there.
So I bought a ticket and flew to Japan for a few weeks in late '05. Have been a frequent visitor ever since. Took up the language study again - this time much more seriously, worked my way through Heisig (well before the creation of this marvellous resource), etc.
To me the language has become at this stage a very urgent first-rate priority: I am looking to relocate to Tokyo (touch wood!!!) in early '08 and the job currently being negotiated (or any other potential job, if this one falls through) involves interacting with the locals in a native-proficiency level environment and would typically be filled in by a local... Needless to say, this is a huge challenge so I'm working hard on it right now.
Now, I'm definitely in a minority on this forum as I positively can't stand anime or manga (with an odd exception that confirms the rule, such as Suzumiya Haruhi no Yuuutsu - which has some brilliant language in it - I recently managed to find an electronic version of the book and was pleased to find that it's actually a Book, not a manga...), so there would be very little incentive for me to learn the language in isolation from the country.
So to me it's all about the ultimate challenge of being able to establish and maintain my existence in Japan. If I manage to go out there next year, there is no return date - as I have no place to return to - having been on the move all my life, I don't have a notion of 'home'. If I ever become disillusioned with Japan, I'm most likely to find myself looking out to new horizons than looking back...