As I slowly sense some improvement in my Japanese abilities, I am somewhat lacking in motivation to continue learning (I'm writing in a good mood, so this won't be too self-deprecating or pessimistic).
Of all the many great ALT's in Sapporo, I have a few close enough friends to satisfy my needs for companionship; and the group as the whole provides enough of a social network to make me feel connected (to provide a party or dinner on the weekend whenever desired). I tend to have a couple friends who I stick to a lot, and I'm not so good at being part of a 'crew', but being here has let me work on both a bit.
As a result, I'm not desperate to make new friends. Rather, I'm lazy and take the easy route through my native language to friendship. A little bit of loneliness would be a good motivator to make new friends!
In terms of functioning here, well, I've already survived four and a half months with no major mishaps. I've settled into a comfortable apathy a lot of the time at work, with enough small-exchanges with coworkers to show that they are accepting of my contracted existence.
When I have to interact with people who don't speak much English, they are usually understanding about the lack of communcation, and we get by with a mix of the two languages and much flailing of the arms and face. As friend Alice points out, you don't need the language to connect with someone, you just need the intention and willingness, a little bit of personality, and, of course, the flailing. Also random conversations with people tend to start up because they are happy to practice their English, not because they want to see if you can speak Japanese.
So, it's hard to pinpoint any external motivator for learning Japanese. The internal motivators are the enjoyment I get from the sense of learning, the interesting nature of Japanese, and the kick I do get out of talking to people in tidbits of nihongo.
Over all, I've relaxed a little bit about the whole thing. I've realised that the learning isn't something I can force upon myself, or guilt myself into. It's not a chore for me to do here - at least, I haven't committed myself enough to it to make it a firm accomplishment I need to acheive.
Instead, I have started to accept more that it is the being here and being happy that are important, and if I commit to being here - instead of focussing on life back home, or life after, or things that take my mind away from this place and this life - then I will learn as I go, and have no reason not to be pleased with my time here.