I have observed the happiest people I know are the ones who help others. And the grumpiest people I know are all about themselves.
Maybe the Bible had more than one reason for all that "serve others" stuff...
I have observed the same holding true to money and power. Some of the most joyful people I've met are dirt poor, under-valued, and lacking for just about everything.
vs.
Some of the unhappiest people I've ever met are rich, "important", popular/famous, and lacking in no material thing.
...but there are many ways to be rich and poor...
*was going to insert the scene from enemy at the gates that speaks to this, but it might be a bit graphic for some...*