Prolonged sitting can aggravate cervical, thoracic and lumbar pain. In an ideal world, frequent interruption of these static positions, every 1-2 hours, is the best method to counteract the ill effects these positions create. Most times sitting puts the spine in a flexed(forward) bias. It makes sense then to move our spine into extended (backward) positions.
Cervical Spine
Place fingers at bottom of neck. Retract(slide) head backward and extend neck (bend backwards). As you do this, push the bumps on your neck downward with your fingers. Hold 1 sec. Repeat 5-10 times.

Thoracic Spine
Lift and reach backward with your arms over your head. Hold 1 sec. Repeat 5-10 times.

Lumbar Spine
Starting from a flexed position, rock your pelvis back and forth, rolling on your sit bones. Hold 1 sec, 5-10 times.

*Adapted from APTEI