There is a beautiful parable in the writings of Luke (11:24-26) that tells of an unclean spirit that is cast out of a man (the unclean spirit's home) by repentance and seeks a new place to reside. The unclean spirit wanders through desert places and finding no new home decides to return to his original home. When he arrives he finds that the house has indeed been swept clean, but it is empty and so the evil spirit invites seven other unclean spirits to join him and they all enter in and dwell there so that the man ends up worse off than he was in the beginning.
The moral of the parable is that even though the man repented and swept his house clean, he didn’t fill himself with something new and good so the old, evil spirit easily returned.
The interesting thing about this is that modern psychological research has shown that in the pursuit of happiness it doesn’t work to just stop doing what is making you unhappy. To become a happy person a major break with the status quo needs to happen. You need to not only stop doing the negative things, you need to replace them with positive things.
Happiness is a choice! It takes work and effort, but everyone who wants happiness can have it. The promise of the Good News! is that man was created to experience joy! (See 2 Nephi 2:25.) and by choosing to occupy ourselves with good, positive things we crowd out the bad.