Even with a computer-based job, there are some things you can do to relieve stress on the neck. If you wear bifocals, beware of moving your head and neck up and down over and over as you switch your focus from the computer screen to the keyboard. Get single focus glasses that are right for the screen and the keyboard. Your local optometrist can help you with this Remember to use them!
Next, even if you can't leave your computer area, take short breaks often. To give your eyes a rest follow the "20/20 rule". This means every 20 minutes, look 20 feet away for 20 seconds.
In other words, change the focus of your eyes to some other part of the room or even out a window if you have one. Make sure your computer screen is at eye level and not above forcing you to look up. There are computer software programs designed to interrupt your work and tell you to take a break.
Shrug your shoulders up and down a couple of times. Take some deep breaths. Reach your hand straight out in front of you and up over your head. Breathe deeply as you do these movements. If you can, just standing up and sitting down again can give your body the break it needs. It's all the better if you can stretch in the standing position.