Its a basic principle assuming that every 'Effect' has an underlying 'Cause'.
People operating in a 'effect' state are allowing actions outside of their control to effect them and therefore start to loose control of their situation. An example for me might be:
"Its my Boss' fault that I lack confidence"
If I were to change my state to "cause", I would acknowledge that I choose the state of no confidence. I can choose to be confident or choose to consider that just because Boss has given me feedback on one aspect of my work it doesn't mean I'm bad at my whole job.
Moving into the "cause" state gives you empowerment and choices.
Check out the link below if you want to understand more about it.
http://www.skillstoolbox.com/CauseAndEffect.php
