Personality
There are of course innumerable causes, but you have requested an illustration. Well, suppose you are having difficulty with some person and you have decided on a certain course of action ‘to put him or her in his or her place’. However, if, when the time comes for action you weaken, this will immediately set up a negative impress. Always, when you decide on a course of action you know to be right, or believe to be right, see it through whatever the costs. Never have second thoughts, unless there are very good reason for them. Whenever you decide to do something and then turn back, it sets up a negative barrier which becomes part of a greater negativity barrier, and this is increasingly difficult to overcome as time goes by. So always, when a decision has been made in your mind, carry it through.
The personality always remains, together with individuality and memory, these being the factors of selfhood. However, personalities can be changed and someone with a bad personality can always choose to make a change for the better. Whatever the personality at transition, that is the personality with which one will reincarnate, but one will be given opportunities to rectify any defects, and every effort should be made to do so.
We all make some wrong decisions, but remember that a wrong decision is better than no decision at all. Indecisiveness should be avoided at all costs.
Personality is the sum total, on balance, of your previous incarnational conditioning. Character is the expression of conditioning in a particular incarnation, and it can therefore modify personality.