Lately I've been noticing that I tend to draw while hunched over, with my face as close as possible to the page. I've been wondering if it's better to sit up straight, although when I do that, I can't see details as well (even when I'm wearing my glasses). Does it matter whether you hunch forward or sit up straight?
Does it matter?
My entire thought about creation of art is "Whatever works for you." There are no rules or best practices directly related to creation. It's only in production where there are guidelines.
Now, that being posted, you may find that you feel better and can draw longer if you just try and take care of your posture a bit more. :)
I developed a habit over the years of sitting with my feet up on something, knees bent, and a drawing board across my legs. This causes my back to stay closer to an upright position while drawing, even if I hunch over slightly to get closer to the work.
I was going to say something about posture, but when you get to my age, it hurts no matter how you sit.
From a technical perspective, there is value in changing your distance in order to both get an overall sense of the work and a close-up view. You have close-in covered. One way to get back from the work (aside from getting out of the chair) is to use a "reducing glass."
A second thought is that you should have the work surface angled such that your viewing angle is perpendicular to the plane of the picture. Many learning artists can't figure out why their precious drawing of their BFF is squashed: it was because they had the sketchbook on their lap at an angle.