Some of us who were bookish kids, who didn't play organized team sports at a young age, believed that we just weren't athletic. If we didn't care much about the most popular sports, if we didn't understand the rules of whatever game we were playing in gym class that day, if we were afraid of being awkward or missing the ball, we bought into the idea that physical activity just wasn't for us. I bought into that myth for years, until well into high school.
At some point, though, I noticed that I liked to dance, and while that wasn't a sport, it was certainly a physical activity. And I liked volleyball, and was lucky to go to a college where the athletic director had made it a sort of mission to get as many students as possible involved in intramural sports, especially volleyball, by emphasizing fun. No longer was exercise something I "couldn't do" or "wasn't good at." I also started to realize that I'd played outdoors in the woods as a kid, and I liked to
walk everywhere--and when you put those two things together, you get
hiking. After college, I joined hiking clubs, and I still make walks and hikes a part of my daily life.
So I suppose there are two conclusions here. First, writing is a sedentary activity, and it's important to balance it out with physical activity. It doesn't matter what--yoga, martial arts, walking, running, tennis, dance, swimming, bicycling--anything that seems fun. And second, sometimes it's good to question our assumptions about ourselves, especially our perceived limitations.