I'm a Web Strategist, so I understand how your Webmaster hubby can spend hours sitting in front of his computer. I used to work primarily from home, but am able to move around with a laptop.
It's important to get out of the chair, every now and then. Sitting for hours can stress your back, legs, neck and more. I developed a very painful shoulder injury from sitting at my desk several hours at a time - caused by using the mouse!
All things need balance, even work.