Tbh, I find myself a lazy piece of shit. But when it counts I put the work in.
I've been on deadlines a bit (flash animation tournaments/competitions) and I generally end up going crazy in the last 2 days.
But if I have an idea I really like, then I'm pretty motivated to just do it. If you have good self-restraint you could just have no internet for a couple of hours so you can work on your animation.
But essentially, if you enjoy what you're doing, you'll have more luck in doing.
Keep in mind this is coming from someone who has a hard time staying on task. But I'm better at giving advice than taking my own, or anyone else's really. My advice is average at best anyway.
"Getting in the mood" is all up to the invididual. But if you set yourself goals then you're more likely to get stuff done.