Okay, so maybe that's a little extreme, so here are some options to consider when dealing with lack of motivation/"writer's block".
=>Take time off from your current project. Maybe a few weeks, or few months not writing will give your brain rest and allow you to start anew. But in my case, taking time off usually prolongs my lack of motivation, it doesn't really help.
=>Take the project in a new direction. Maybe your subconscious is stopping you because you are working your way to a dead end, and you need to rethink the plot so that your story will become what it is meant to be or whatever.
=> Work on a different project. Working on other story ideas, or other creative projects may rekindle your desire to work on the story that's stuck.
=> Get your life in order. It is possible that you are not motivated because you have other life issues that are haunting you when you try to sit down to write.
=> Re-prioritize. Maybe nothing is wrong with your life, as you see it, but you might be dedicating too much time to your miniature model-T sets, which not only strains your eyes, glues your fingers together, and expels fumes that give you flash backs from the 1880's; but also makes you too exhausted to finally sit down and finish the next great American novel.
Okay, you can't lose the job (or you'd be homeless) but you can cut down on bear wrestling (sorry bears, I know you love the "cuddles") and you can cut down on the miniature model-T's (sorry Henry Ford, or should I say Nazi Ford? That's right, I know your secrets Mr. Ford and I will share them with the world, once I get enough motivation to finish my novel!), that will allow you about 6 minutes and 43 seconds a day to work on that novel. If you type 50 words a minute and the average book is 80,000 words long (give or take 20,000ish), 50 over 60 equals .8333333333 words per second and you've got 403 seconds a day of writing time, carry the two, and you've got 335.833333333 words a day, divide 80,000 by that and in 238.2 days you'll have your first version (or rough draft) complete for your novel. So, about 6 years per novel. Should you quit now, maybe, that's not for me to judge. Does this scenario make you even less motivated?
Probably.
It definitely demotivated me.