From Mere Christianity, CS Lewis writes...

"In other words, fallen man is not simply an imperfect creature who needs improvement: he is a rebel who must lay down his arms.  Laying down your arms, surrendering, saying you are sorry, realizing that you have been on the wrong track and getting ready to start life over again from the ground floor - that is the only way out of a 'hole'.   This process of surrender - this movement full speed astern - is what Christians call repentance.  Now repentance is no fun at all.  It is something much harder than merely eating humble pie.  It means unlearning all the self-conceit and self-will that we have been training ourselves into for thousands of years.  It means killing part of yourself, undergoing a kind of death.  In fact, it needs a good man to repent.  And here comes the catch.  Only a bad person needs to repent: only a good person can repent perfectly.  The worse you are the more you need it and the less you can do it.  The only person who could do it perfectly would be a perfect person - and he would not need it."

Repentance, in the true sense of the word, is really not fun at all.  To understand that I am completely going against God and not simply a little off course is knee-buckling.  To die to the part of SELF that is still alive and wanting its way is painful. 

I do love the 'riddle' at the end of this quote.  My heart resonates with it as I want to repent perfectly, but even in that I know I can't do it, because if I could, then I wouldn't need to.  The only way I can repent, is by not doing it myself, but dying and allowing Christ to do it.  Painful... but ultimately very freeing.