Having multiple projects going has worked for me as a way around that, fwiw. Haven't yet been blocked on everything at once.
I'm always a little wary of "push through"-type advice because I've seen successful published writers irrevocably screw up WiPs and be unable to finish them because of trying to push through something that needed to be mulled on more first.
Yeah, I should throw in a "mileage may vary." I'll stop for a few days for research and such, I definitely aren't saying "write every day whether you feel up to it or not." But when I realized I haven't touched it for two or three days, I sit down and make myself at least hammer some work out.
For me, "Pushing through" probably works so well simply because I've got the entire story arc, along with several milestones mapped out already though, so I know where I'm going and it's usually case of working on the "boring" stuff between the last Exciting Cool Scene and the Next Exciting Cool Scene I've already imagined and simmered in my head for a while. And once I sit down and do a couple hundred words of work, it usually turns to play when I'm not looking.
Usually, for me the biggest problem is getting started. It's like a restaurant you really like but just don't feel like getting out of your pajamas and getting dressed to go to. But once you're there, it's just dandy and you're thinking "Damn! I should have come here yesterday...."
