An Iceberg is a really good way to illustrate our conscious and subconscious minds. You see from the surface a pretty good chunk of ice; but the vast majority is below the surface. This is just like our mind. We have a conscious awareness that contains logic and reason, willpower, critical thinking, etc. Then, there is the sub conscious, or un-conscious mind. Pioneers in psychiatry, like Sigmund Freud and Carl Jung were aware of the subconscious in the early part of the last century. The subconscious contains our primitive mind that some people refer to as our "reptilian" brain. It keeps us breathing, eating, procreating, and kicks in a "fight-flight mechanism when we are threatened with mortal danger. It also stores our modern memory: From the time we're in the womb until the present moment. The subconscious does not sleep! The subconscious is 88% of our mind, and it's not the logical or reasonable part. It contains only positive and negative associations of pleasure and pain. knowns and unknowns.

Our subconscious HATES  unknowns!! It's interesting to note that our subconscious  will stick with a known, even if it's bad, wrong, or not beneficial to us, rather than venture into the unknown. That's why people continue to smoke when they know it's not good. Stay in bad or abusive relationships. Keep plugging away at dead end jobs they hate, and so on. The status quo is always preferable to the unknown.

As the saying goes: Willpower is only good when you don't need it.

You can't reason with your subconscious.

If you say: "I gotta stop eating cookies every day." Your subconscious might very likely respond with: " No I don't!"  Guess who wins? The 88% that's under the surface. Hypnosis is a safe and valuable way to bypass the critical filters we all have in place, reach our inner-conscious mind, and re-write our reality.