Using the correct chair and computer desk can protect your whole spine from postural strains.
Here are a few tips 

1. Work directly facing the desk and computer.
2. The monitor should be at eye level where your eyes are directly looking at the top 1/3 of the monitor. A document holder attached to the side of the monitor can make manuscript-typing more neck friendly. 
3. The keyboard and mouse should be around belly-button height and close to the body.
4.It is better if you can angle/tilt the front of the chair, so that the thighs are angled downwards.
5. If you spend a great deal of time talking on the phone, try using a headset. This will help you avoid cradling the phone between your ear and shoulder. Headsets also allow both hands to be free.
6. Regular breaks should be taken every 30minutes. Stand up raise arms above the head looking up at the ceiling then roll your shoulders backwards 3 times as you walk around for 1 minute.

 

Another way to decrease strain on the lumbar spine discs is to stand at the computer as shown in the following diagram.