To perform the neck roll downs, lift up gently through your chest bone. Now begin to bring your chin towards your chest and allow your neck to steadily lower the head down towards the chest. Imagine as you move down, as if you’re moving your neck down segment by segment towards the chest, until you reach the end of the movement. The movement should only be coming from the neck, therefore do not allow your chest to slump. As you lift your head up, initiate the movement from the base of your neck, finishing the last part of the movement as the chin lifts up.
Continue several times with the movement, the emphasis being on quality and smoothness of movement and not on strength.