1. Stand up straight next to a wall placing your left shoulder against the wall.

2. Try and lift your right leg.

You can't!

Here's why:

Your Body Is Made To Move ( Motion-The 1st Posture Principle)

You can't shift to the left in order to balance.  Walking involves lifting one leg and balancing the other with SHIFTING and STANDING muscles.  Up Against The Wall shows how unconscious motion has real world effects.  This is why people often balance better after a chiropractic adjustment- Areas which are locked affect balance, which the adjustment unlocks to strengthen balance.