2 Corinthians 7:10
Because the sadness that is according to God produces repentance for salvation, that there is no need to repent; but the sadness of the world produces death.
In our daily walk it is not enough to feel bad for the bad actions of the past. The feelings of guilt are only the beginning. One may well feel pain remorse for having done something wrong or having been discovered in error while still doing the same thing that causes pain ie without repenting.
Source
That is why we must truly understand what is repentance? How does it differ from remorse? In what does "the sadness that is according to God" help us?
Repentance leads to the restoration of the soul is a change of mind that results in a change of behavior.
because to repent is a regret that you feel for having done something that has obviously been wrong between your principles and values.
However, remorse is only mental torture, a bitter feeling of guilt for the results of bad action. Unlike true repentance, remorse never leads a person to positive and corrective actions.
That is why when we read the story of Judas about his actions we realize that he did not repent but felt remorse for his actions. Unlike Peter who when he denied the Lord wept with repentance he felt pain and sadness for having denied his lord and his deep drowsiness led him to a true repentance
Judas took his life because his act led him to remorse while Peter's act led him to a change of life because he repented and we remember that the sadness of the world produces death.