Autohypnosis is about rewriting and reprogramming conditions of the subconscious that were passed along to us genetically. Or even incurred.
You see, every human first 7 Years is download to hypnosis. Most of the results we get in life have their roots from how we lived life in the first 7 years.
So autohypnosis is an aspect of hypnosis that's powerful enough to rewrite those programs we downloaded from parents.
Repetition is not enough to reprogram those Footprints from the subconscious, or at best, is too slow.