The over-analysed writer
I don't mean over-analysed in the English Literature sense, where sixteen pages of hidden meaning can apparently be wrung from one paragraph of a novel. I mean, loosely, in the sense of data analysis. I read an interesting article in the Guardian this week (and believe me, I don't say that very often these days) which looked at graphs of writing progress for one author on his way to a finished novel, courtesy of an app he'd used to log these things. Cheering to most of us, I expect, was the up and down nature of the thing, the long pauses where life intervened and writing was something that happened to other people, or the stumbling recovery made up of several days of adding a sentence, a paragraph, nowhere near target.

My NaNoWriMo progress during November 2016
Now, if you've been around here a while you will have guessed that I've been measuring things like wordcount totals on spreadsheets for years. It was probably during one of my attempts at NaNoWriMo that I realised the motivational power of a graph with a line showing where the wordcount should be, and columns representing my actual total. Certainly it was through use of a daily wordcount tally that I realised how quickly a couple of hundred words in the library in my lunchbreak became a short story, a novella, a few chapters of a novel. There is a flip-side, of course.
I imagine that even for those writers working to a publisher's deadline, life will intervene sometimes. A family emergency, illness, even the temptation of a sunny day after a fortnight of rain. Wordcount targets will not be met. It's clear, therefore, that for everyone writing alongside a day job and family (I don't just mean children, you do need to spend time with your spouse or your sister occasionally if you don't want them to forget who you are) this will happen a lot. If you're writing with hope but no fixed publication deadline, anything you've written that wasn't there last month is a bonus. Look at that sharp red target line floating way above your little blue column, though, and it's easy to get discouraged. What was I thinking? I can't write a novel, it'll take years. I've missed my target twelve days in a row. It may be your targets are over-ambitious, but that's another matter.
In the semi-rural fantasy novel I'm writing at the moment (I don't think that's a real genre, I started calling it that as a nod to urban fantasy but a lot of it is set in northern villages and moors) I've had days when I've written nearly 3,000 words and wondered how I managed it, I've had whole weeks where I've written nothing. I will have written something else because I don't have a regular day-job now, but not the novel. I'm a great fan of conditional formatting, so on a day when I've written at least 500 words of the novel the cell goes green when I type my wordcount in and I smile a contented smile. Simple pleasures. Crucially, I don't have any targets. I don't count non-green-cell days as failures. I try not to have too many consecutive blank days, but how many is too many?
Try an app, try a spreadsheet, try writing your target and actual wordcounts on the calendar in the kitchen for a month. One or more of these may give you a boost and keep you going. But if you find yourself being frozen by fear of failure, or beating yourself up over missed targets, ditch them and focus on the writing.