Imagine your unconscious mind is the hard disk of a bio-computer with its own operating system and software that runs your current life.
You unconscious mind is irrational and deals with habitual behaviors. It cannot distinguish from negative or positive, it just replays programs (habits) loaded into it since your were born.
Your conscious mind deals with rational decision making, it also acts like a filter for all the noise and information that bombards you all day long from your environment.
Your conscious mind hates multitasking and it prefers doing one activity at a time. Under stress and when forced to multitask, as many of us do in this hectic modern times, its ability to protect your unconscious mind from negative information is disrupted.
Sleight of hand magicians and stage hypnotists take advantage of this fact when they distract their subjects and bypass the rational conscious mind planting suggestions into the unconscious.