Paralyzed by Too Much To Do

I have to write 3 training courses in the next 3 days. I've been trying to get started on the first one all morning, but I find myself utterly paralyzed by having so much to get done that I don't know where to start. There is no legitimate way to get it all done WELL in the next 3 days, so I've got to do a half-assed job and be okay with it. That is not something I'm good at. Okay, diving in, again.