Sitting on a chair continously for long hours can leave you with acute pain in your neck. Once it gets triggered, it ruins the entire schedule and makes you irritated. Here is a small exercise which can be done in the office while sitting on a chair with less of effort and time but the relief is long-lasting:
Method:

-Sit on a chair, loosen up yourself. Keep palms downwards on your knees. Breathe normally and keep your back bone and neck erect.
-Inhale, and then exhale completely while moving your neck to your right side and try to look back as much as you can.
-Stretch your shoulders backwards. Retain the posture for a while. Now gradually bring the neck back to normal position while inhaling.
-Follow the process on to your left side. Repeat the exercise for 4 to 5 times.