In Chapter 4 of Hilkhot Teshuba Maimonides enumerates twenty-four actions or personality patterns or attitudes that prevent or make very difficult for a person to begin or undergo the process of repentance.
DOMINO EFFECT (4:1) Those who because of their teachings or their bad example, etc. induce or influence other people to sin, causing a negative domino effect. Teshuba, in this case, is virtually impossible because part of the process of repentance is repairing what one has done wrong. Once one prompted or influenced other people to do the wrong thing, how could he repair the damage he caused? From a practical point of view, he is beyond redemption, because despite his own personal repentance, his teachings are still exerting a negative influence in others to an unknown extent.
CALCULATED TESHUBA (4:1) Sinning with the intention of repenting later. Maimonides refers here to a situation in which I'm about to commit a sin and I tell to myself "I can repent for this sin later on." Or: "Since Yom Kippur is a day of forgiveness , God will forgive me for the sin I'm about to commit". In these conditions Teshuba is unacceptable. Because Teshuba is accepted by the Creator only when it comes from a sincere remorse, not as a calculated game plan.
DEFENSIVE PERSONALITY (4:2) Someone who hates to be corrected or criticized. Imagine a person incapable of accepting a minimal dose of respectful criticism, even when coming from those who care for his or her well being. Many times, this type of personality disfunction is a consequence of a low self esteem, which prevents a person to cope with any rebuke because his self esteem will collapse. This person, Maimonides concludes, will likely continue with his or her bad habits because he is incapable to allow himself to see himself as other people perceive him. This is one of those cases in which you cannot help those who don't want (or cannot) help themselves.
Great people talk about ideas.
Average people talk about things.
Small people talk about other people.