WOW, I’m impressed!
What kept me going when I wanted to quit? I separated my office from my home life and worked 10 hours a day in the office. After that, my time was my own. This is a huge secret for those of us who work for ourselves or have some other huge project to do in an unstructured time frame. I’ve always treated weekends and holidays as just another work day. Donig that left me tired and eventually burned out. Once I started taking weekends at least, spending them doing weekend-y things, I suddenly felt like I had more time. Go figure. The only way I was able to write my book was to use this tactic. In my case, I had a weekly writing goal, and whenever I didn’t meet it, I had to write on weekends. The goal of having that free and clear time off inspired me to keep working when I’d rather not have, and I also enjoyed my non-working time more.
It sounds like you had a hard deadline and so had to push yourself that hard–10 hours per day is a LOT! For those of you who are writing books or have other long-term projects, it’s important to only push yourself a sustainable amount so you can avoid exhaustion and keep going.
On the other hand, putting yourself through something so intense and coming out of it well can be an inspiring memory that you can compare to other things you face. For example, when you have something huge, demanding and scary, you can always say Well, I got through THAT, so I KNOW I can do this.