There is said to be two main reflexes in the body. One reflex is used for forward motion , the other is used to retreat . The forward motion reflex lends itself to a structure that is very open in the front. There is a time and place for this, but some people use it in an unbalanced way. People who are always rushing to get ahead or who are impatient, will often find an excessive anterior tilt in the pelvis.
Some people are lazy, but still waiting impatiently.
These people will also find this tilt in the pelvis. The opposite of this reflex is the second reflex of retreating. People who are very afraid will often close up the front of their body. They contract their abdominals pulling the pelvis into a posterior tilt. Their arms hang forward, their ribcage collapses.