Essential Running Stretches

Heel dip. Stand on a curb or a step with the tip of your feet, lower your heel as far as you can, hold for a few seconds, return to upright.
Touch your toes. Stand with legs straight, bend down as far as you can and try to touch your toes (or the floor).
正座 (seiza). Kneel on the floor, then sit backwards onto your legs.
Leg pull. Alternative for above if the ground is rough. Stand on one leg, pull the back of the other to your bum and hold. Alternate legs.