Keep your shoulders relaxed. Looking straight ahead tilt your head down. Then slowly stretch the neck back, gaze slightly upward.
Lower your head again looking straight ahead and repeat.
With your shoulders straight and your gaze straight ahead, bring the ear to corresponding shoulder. Bring your head to the center again, and without stopping the movement, bring the other ear to its corresponding shoulder.
Repeat. From top to bottom, draw with the jaw an imaginary line from top to bottom down.
Always looking straight ahead, draw the same line from bottom to top and repeat.