First, as the article points out, a lot of creative endeavors, including even writing, can tax the body:
As a yoga teacher, Bobowicz was concerned about the repetitive stress that plagues artists as they work.
"Jewelers can hammer over and over again, painters use their hands and wrists to do brush strokes, and writers crouch at their desks and type -- stress that builds up on important parts of the body can become a block so the creative force can't flow through," Bobowicz said. "We want to keep these body parts open and healthy. I see this as occupational therapy for artists."
For writers and others who are sedentary, that's also a big problem.
Beyond that, getting passionately involved in yoga or any other endeavor can take the pressure off your writing.
Finally, physical exercise is a great catalyst for creativity, and many people (including me!) get useful ideas or fresh perspectives while walking or exercising.
So...good idea to incorporate yoga or another physical activity throughout your day.