Remember that the subconscious mind is where our [magic] creative power resides. See Getting Past The Censor, Taking Your Magic Back for details about that.
Your subconscious does NOT know how to process negative logic though. This is a primary reason Christianity is such a difficult practice. The 10 Commandments are mostly “Thou Shalt NOT…”.
Now since the subconscious mind does NOT process negatives, what gets in is the very thing you wish to NOT do. This sets up a conflict between your conscious mind and your subconscious where you consciously wish to avoid doing “wrong” but your subconscious mind vegetates on doing the very “wrong” you wish to avoid. Paul lamented this very state on Romans 7:15
"For that which I do I allow not: for what I would, that do I not; but what I hate, that do I."
Focusing on the negative, such as “I will NOT commit adultery”, will set your subconscious mind to looking for adulterous opportunities.
For self development, Magical or otherwise, it is far better to focus on positive statements. Instead of “I will NOT commit adultery”, use a phrase such as “I WILL be faithful in my relationship”. Get your subconscious focused on the positive concept of what to seek rather than the negative concept of what to avoid.
Since the 10 Commandments are primarily “Thou Shalt NOT” statements, it sets up a continuous battle to AVOID undesirable behavior. This is likely intentional, and is a level of dark magic, being subtle in nature makes it a rather high level of dark magic. The Bible is after all a Book of Magic…or Spells…a.k.a. a Grimoire.