This is exercise is a basic activation and strengthening exercise for the whole neck complex, and can be effective at reducing neck pain.
Demonstration and Instructions
Sitting tall, gently lengthen the back of the neck and tuck the chin down. Place one hand at the front of the forehead, and gently press the head into your hand, without actually moving your head. Feel the tension in the muscles, and hold the contraction for 5-10s. Repeat this to both sides of the head, pushing your head to the side (as if you were taking your ear to your shoulder), and finally at the back of the head, as if you were going to look up towards the ceiling.
Special Notes
Ensure you maintain a good posture throughout the exercise, and the chin tucked slightly in. Only push as hard as you feel comfortable, there should be no pain.