I have back pain. Now I have less back pain. You can, too. And it can be a simple and free improvement that takes only a two-minute rummage through your garage, which you've meant to go through anyway. The fix: raise your workstation. Stand while you write and surf the web. Sit less. When you stand you tend to move around more, which keeps blood circulating and muscles moving.
My DIY solution is very basic, and temporary. I just propped up my laptop on a wire shelf and plastic tub. I plan to do a more substantial solution soon. But for now, my laptop is up high and I am standing while I work. Lifehacker has more and better ideas about how to do this, here.