On Google Docs, I keep a spreadsheet that tracks my progress. Every morning, after my writing session, I hop in here and update my word count. The document automatically calculates a number of statistics that tell me where things stand:
All I have to do is update the "Current Count" column. Everything else is calculated automatically, and instantly I know how far ahead, or behind, I am.
There's something quite addictive about seeing the numbers climb, and not just my word count, which I can get within Scrivener very easily. What's more motivating is seeing that "ahead / -behind" field grow and stay blue. It turns red if I'm in the negative, and I despise seeing that color here. When it's blue, I know I'm ahead of schedule, and the translation into days is even more powerful.
On days when I'm struggling to get through a scene, I find myself updating the word count often. Like, every hundred words or so. Each little update is a reminder that I'm making progress, even if it's at a snails pace.
As you can see, right now I'm working towards a self-imposed deadline of May 15th to finish the second book in this trilogy. Contractually, the book isn't due until August 15th, but I'm striving to finish it early so that I have more time to work on book three. Even with my early May 15th date, I've managed to build up a nice bank account of days ahead. Seeing this number is a fantastic and tangible reward, because I know two things: first, I can take a day off here and there without stressing about it. Second, I know that every day ahead I get will be a day I can use to polish the manuscript even more. If I can keep up my pace, I'll finish a month ahead of my personal goal, a month I can use to go back and fix all the problems I've already noted.
A spreadsheet like this is especially useful when you're behind. Primarily so that you'll simply know you're behind. It can be difficult to gauge something like that on a project lasting many months. But not only will this tell me I am behind, it'll tell me what my "new average target" needs to be if I want to finish on time. It can be unnerving to know you're behind by 6000 words, but when you see that all you have to do is up your daily goal from 600 to 650 words to finish on time, the obstacle doesn't seem so daunting.
Every project I actively work on goes on the sheet, and I used this even before I had an actual deadline to worry about. You may have noticed there's a column for "writer" here, too. This sheet is also used, on occasion, by members of my writing group, and the multi-user aspect is a great way for us to keep each other honest. Praise when we see progress, and encouragement when we're lagging.
Since I started writing, I've always set myself a date to finish something by. Even arbitrary dates serve as a great way to give yourself a path forward, and the spreadsheet acts as a visual way to wrap your mind around the enormity of your project.
As they say, nothing spurs creativity like a deadline.