Getting back on the horse (again)

What's to do when circumstances keep one from a project? Berate yourself? Or get back on the horse?

In June I was cruising for a while, writing very productively--if I had kept that pace, I would have reached 60,000 words by now. I didn't. Should I hang my head in shame? Should I spend time lamenting what was lost? I don't know, but those don't seem like they will help me finish the book. If I spend time lamenting what was lost instead of working on the book, won't that give me something to lament in the future: the hours I spent lamenting instead of working?

So I want to get back on that horse every time I fall off, as quickly as I can.

I'm over 44,000 today (thanks, partly, to finding 1000 words I wrote years ago that will suit).

It may not be graceful, but I'm riding again.