You need to improve your posture at the desk
Probably you are working long hours every day. How many hours do you have to sit in a chair for an entire day? Spending too many hours at your desk will have some problems for your body. You need to improve your posture when you are working.
What to avoid
Sitting in an uncomfortable position
If you are sitting in an uncomfortable position, you have to change how you to sit. Make sure that your eye level to see the computer and your arms are supported comfortably.
Sitting too long without getting up
You have to get up and stretch or walk around at the office at least twice a day.
Uncross your legs under the desk
The correct way to sit in a chair requires you to place your feet flat on the ground. That means no crossing your legs or sticking them out in front of you.
If making your feet completely flat is uncomfortable, prop your feet on something. A small laptop stand or some old, thick books could work as makeshift props.