The neck
Be careful when warming your neck not to tilt your head too far backwards. Move slowly or you have risk of injury, which would be a shame before even hiking!
Relax your shoulders and tuck your chin in toward your chest while breathing out, then tilt your head gently backwards while breathing in, and repeat 20 times.
Do the same thing while looking sideways, first left then right, 10 times each side.
Finally, circle your head 10 times in one direction then in the other, as slowly as before and without tilting the head too far.