I just wrote a hub concerning this question. http://hubpages.com/hub/ispositivethinkingconsiste...
We cannot positive think away a deception because it is not real. The deception that we have a problem, in fact means we are the mistake. If we did not believe this, we would not try to fix the problem with things such as positive thinking. It is not that positive thinking does not work, but it is impossible for it to work under deceptive guidelines, which means the problem is coming from "out there" and you can magically fix what is out there by saying some magic words to yourself. You are not wrong, it is your perception that is in error concerning your Self value.
Terms such as bad boy or girl, or feelings of unworthiness has left our Self in a world that does not understand a proper perception of integrity. If we believe we are bad, magic words will not resolve this issue. This is a perception problem, and positive thinking cannot correct perception. The gaps in perceptive integrity has left us feeling like we are missing something, and we mistakenly believe we can make this up by filling in these gaps with words that do not really have access to the integrity necessary to change the problem. Personal integrity is value. When our words do not hold the integrity necessary to fill in the gaps, the problem remains. This integrity is like something we can't quite remember. A feeling like something is lost, and if we could just find it we would feel much better. Self integrity is not lost, it just has been misplaced.
Until it is recognized that all problems can be eliminated by redefining perception, we will continue to attempt to do something to fill in the blanks with a false remedy we hope will work. By doing this do not have to address what is really wrong, which is that the integrity within the Self has been damaged, and our perception concerning this needs an adjustment.