Have a little fun with these neck rotations and do your best impression of Linda Blair's character in The Exorcist while doing them. Just be sure to keep the swearing to a minimum if you're in public. Kidding aside, we carry so much tension and stress in our neck and shoulders, neck rotations will release the tightness and improve flexibility that is vital to the flexibility required for safe driving and situational awareness.
Turn your head to one side as if you were rotating your head around a vertically oriented axis. Deepen the stretch ever-so-slightly by looking as far to the side as you can. Continue the stretch for 5 seconds then return your head facing forward. Repeat x10 then turn your head in the other direction and repeat. Avoid tilting your head and bending your neck and don't force any movement.