Regardless of how good your working posture is, working in the same posture or sitting still for prolonged periods is not healthy. You should change your working position frequently throughout the day in the following ways:
Make small adjustments to your chair or backrest
Stretch your fingers, hands, arms, and torso
Alternate between seated and standing positions while you work
The four working postures above are examples of body posture changes that all provide neutral positioning for the body.