Wonder why you feel tired and exhausted sometimes after using the computer? You may be suffering from "email apnea" - a term that refers to how about 80% of computer users stop breathing while typing. This can trigger the sympathetic nervous system (SNS) and put us into "fight or flight mode."
I do a lot of work in front of the computer and I have to remind myself to do some yoga while working. It's easy to do some "chair yoga" while sitting at your desk. Sometimes it's as simple as doing a twist in the chair (I grab onto the arms of my office chair and turn to each side). I also stretch my back and shoulders as frequently as possible - especially because they tend to round forward when I am doing computer work. I also work on my wrists, especially because I have a bit of a repetitive stress injury in my right wrist.