Gratitude

The single key measure of life satisfaction is GRATITUDE.

Watch how someone reacts when you give them a gift. The happy, fulfilled person will be grateful even if what you give them isn't a lot. 

The entitled person discards the gift or finds some reason albeit subtle, to belittle it. They might even demand more.

Then generalize this attitude to every object, person and circumstance in that person's life to see how they see their own lives. 

Then understand this is exactly how they feel about themselves. The first person is at peace. The second person feels nothing is ever enough.