The correct posture while sitting at work involves keeping your back straight, shoulders back, and your feet flat on the floor. The following are some tips to help maintain good posture while sitting at work:

1. Keep your chair at the right height so that your feet are flat on the floor and your thighs are parallel to the floor.

2. Adjust the backrest of your chair so that it supports the natural curve of your lower back.

3. Use a lumbar roll or cushion to support the natural curve of your lower back.

4. Keep your shoulders back and relaxed, and avoid hunching forward.

5. Keep your head up and in line with your spine.

6. Use an adjustable keyboard and mouse to keep your wrists straight and avoid repetitive strain injuries.

7. Take regular breaks to stand up and move around, to stretch and change your position.

8. Adjust your monitor to eye level to reduce neck and eye strain.

It's also important to note that it's not just about having the right posture while sitting, it's also important to move around and change positions regularly to avoid prolonged sitting in one position which can lead to muscle tension and other health issues.