I once read an article about how the CEO of a large company takes a day just to think, maybe walk, do low-impact activities, but mostly think. There are many articles like this, and I think more creatives should follow the pattern.
As writers, our 'work' is more like play and it's a lot of fun, but it's also a lot of concentration, planning, brainstorming, and you know, work. Since I entered the online writing community, I kept hearing the same advice about how writers succeed. Write. Write everyday. Write on the toilet. Write in your sleep. Eat, sleep, and breathe writing. Only then will you become a good writer. But not all advice works for all writers, and not all writers can write everyday.
Whether you're in the 'write everyday' camp or the 'write when I can steal a moment' camp, we can all agree on one thing: we need downtime. You can't write every moment, and you shouldn't. You need time to recharge, to stir up those brilliant ideas that keep the words flowing. You need time to read other writers' books. Even your dream job can cause burn-out if it's all you do.
Vacations from writing are okay. Taking a few weeks to read, to paint, do pottery, travel, and do anything else is fine as long as you can spare the time. If you're on a deadline, you might only be able to afford a day or even a few hours, but you should take it. Make time for thought and reflection, for turning over those plot problems and looking at them from all angles.
Most of our writing problems aren't solved by writing. Considering a scene, talking out a character concept with a friend, and stepping away from the keyboard awhile can help us avoid a lot of pitfalls in our final draft. We need to grant ourselves 'free' days to gain perspective.
Schedule yourself so your free day feels like a treat. If all your days are free days it won't seem so special, and you'll waste it. (Writing days are not free days.)
During your free day, do fun things, relax, but be sure to think productively over what the rest of your week will be like. (Hudson's Productive Thinking model might help with that) Inspire yourself with art, books, music, and especially your own project. Get yourself motivated so when you go back to the keyboard, you're ready to work. It'll be easier when you do.
So, give yourself a day off. Relax, have fun, but most of all, think.