a) The plethora of resources out there. Japanesepod101.com is the latest I've got into - especially the flashcards (for building up vocab), but there's a lot more than that.
b) The thought that, even though research and other work-related stuff takes up much of my time at the moment, I have more head-space to call my own in summer than I will when I'm teaching. I should use the opportunity!
c) The fascination of the subject - which I've never felt before when learning a language.
On the other hand, I'm restrained by:
a) the knowledge that there's only so much my head will absorb in any one day, and any effort exceeding that is wasted - or at least encounters the law of diminishing returns.
b) the suspicion that this is all a vast displacement activity, and that I would be better occupied either working on the deep causes of my obsession or using it more productively (e.g. by writing fiction).
I'm also occasionally assailed by despair. Like a couple of days ago, when I did a cryptic crossword with my mother, and thought, "I'll never know another language well enough to be able to do the equivalent of a cryptic crossword in it. The most I can hope to do is paddle in its shallows, when it's the vasty depths that call me."
In other news, I've read in a couple of places now that the kanji are very "logical". This, I've got to say, is an exaggeration - even taking into account the Chinese whispers effect (to coin a phrase) of filtering them through centuries of history and thousands of miles of space, with all the differences in world-view, assumptions, technology, associations, etc., that that involves. But their fascination is no less for that, and some are very beautiful in their melding of form and meaning. I'll try to put up some of my favourites here from time to time. To get us started, here is the kanji for tide:
It's made up of the elements for water (seeping up the left-hand side) and morning. But morning itself is composed of the elements for mist and the moon, so we are at liberty to unpack it and see the tide as the water being pulled about by the moon, while we stand watching the waves creep up the beach, ever more clearly visible through the dissipating morning mist.