Most people relate stiffness with getting old, but in today's world many young people are having more and more pain and stiffness due to computers and smartphones as well as sitting too much.  X-rays show that signs of Osteoarthritis of the neck (cervical spondylosis) are present in as much as 50% of those over 50 years of age.   Is this a disease or is this the result of not moving our heads enough?
What happens if a door is not opened for a very long time? The hinges usually freeze up and the door will no longer open.  If we squirt a little WD 40 into the hinges and start moving the door hinge eventually it will loosen up and the problem is solved.
Our neck is similar to the door hinge and will freeze up if not used. We have muscles that are pulling in every direction causing compression on our neck. Our muscles attach at the base of our skull and continue down to the ends of our shoulders and down our back. As the pain and stiffness increases, the muscles will tighten and create more compression which will cause bulging discs and pinched nerves sending tingling down your arms.
During the day, take a break and sit up tall in a hard back chair. Place the palm of your hand on the crown of your head. Tuck your chin and gently pull your head downward using just a little more than the weight of your hand.  Hold for 2-3 seconds and repeat 8-10 times.  Now rotate your head to the right and pull down, with your right hand, as if your nose was pointing at your right breast.  Hold the bottom of your chair with your left hand for stability.  Finally repeat on the left 8-10 times as well.
1-2 times a day look up toward the sky and apply a little pressure from hands to your chin lifting up your head.  This will give your neck a nice little break, some lubrication and relieve your stiff neck.