I had lunch this week with a writer friend. We talked about our current projects. She mentioned that she was having trouble staying connected with the revising of her novel, even though she was spending many hours a day. When she mentioned that she'd given up her exercise program, both through inertia and time constraints, I had to bite my tongue.
Writing of all sorts is hard work. It's not just mentally hard, working your right and left brains in coordinated fashion, but also physically hard, as most writing occurs sitting down. And often sitting for long periods. This is hard on us human creatures, who were intended to move and stretch and reach and bend and be active.
So let me put in a plug for regular exercise as part of your writing/creative life. Some early advocates of writing like Brenda Ueland and Dorothea Brande believed that any plot difficulty could be worked out in the writer's daily walk of 5 or 6 miles. Even at a good clip, that's more than an hour of fresh air, natural stimulation, movement, deep breathing, and reverence, if you're so inclined.
I've been going to the gym four or five times a week for many years. I do the treadmill, back and abdominal exercises, life weights for arms and back and shoulders. I have a buddy and we go. Do I enjoy it? No. But I always feel better for going. When I'm away on writing retreats, I talk a walk or two on the beach or through the country nearly every day. There's something "sortative" about walking. It's a chance to think and resolve issues, to sort things out. And it makes sitting easier to handle. I always come back with a renewed spirit.
So whether you write (or paint or sculpt or pot or weave) for long periods of time or briefly each day, I recommend paying attention to the body's needs for food, rest, and exercise.