Writing your novel is a job or a hobby, whatever it is, don't make it stressful. Giving yourself some quality time will reflect in your written word.
When you write, relax and get up and move around in between paragraphs or chapters. The blood flow stimulates the brain and walking around will prevent thrombosis in your legs.When travelling by plane we all ensure we protect our legs from thrombosis.
We rotate our ankles and stretch our legs, so why do we forget that sitting for several hours while writing is any different? Thrombosis danger time is two.
While you are sitting writing, rotate your ankles keep the flow going and make sure you are active after each hour.
Rocking back and forth on our butt while typing can lead to a form of sciatica. Ensure you release your pelvis regularly.
Get up and make a drink, go for a walk; anything just stretch those legs. The oxygen in your lungs will help the blood flow to your brain, and a different environment can stimulate new ideas. Do a few body stretches and massage your fingers and wrists, this helps stop inflamation forming. You do need those hands!
Arms and shoulders suffer while leaning over notepads or computer. Rotate your head side to side and raise your arms to the sky. Stretch and wave them around. Pretend you are a tree! Laughter is good for oxygen intake.
This will help release tension in the shoulders and neck muscles.
Ensure you get plenty of fluids, have water between the coffee, eat good foods for brain stimulation don't just snack on junk food.
The herb Rosemary is a brain stimulant, have some near you when you write, the fragrance will help you keep the ideas coming.
If you are stressing, have some Lavender close by, it can help calm you down.
Following those few simple rules will benefit you and your writing in the long term.