The difference between joy and entertainment

"Positive emotion alienated from the exercise of character leads to emptiness, to inauthenticity, to depression, and, as we age, to the gnawing realization that we are fidgeting until we die."
 - Martin Seligman

Addiction is, among other things, the attempt to achieve happiness by increasing the number of happy moments in your life.  The above quote relates why it doesn't work.  Long-term happiness comes from actually doing something that arises from your character and leads to a positive result.