The most dramatic instances of directed behavior change and "mind control" are not the consequence of exotic forms of influence, such as hypnosis, psychotropic drugs, or "brainwashing," but rather the systematic manipulation of the most mundane aspects of human nature over time in confining settings.
The 'self-image' is the key to human personality and human behavior. Change the self image and you change the personality and the behavior.
To change a habit, make a conscious decision, then act out the new behavior.
More often than not, the belief that you are bad contributes to the "bad" behavior. Change and learning occur most readily when you (a) recognize that an error has occurred and (b) develop a strategy for correcting the problem. An attitude of self-love and relaxation facilitates this, whereas guilt often interferes.