Questions to ponder from Philippians 1: "Joy not Resentment"

Despite terribly difficult circumstances, Paul bubbles over with joy as he writes his letter to this little church.

1.  Is there a meaningful difference between happiness and "joy"?

2.  Paul often invites them to "rejoice in the Lord". How do we do that?

3.  What tends to bring you greatest joy in life?

4.  What drains you of joy most quickly?

5.  In practical ways, how do we stay free from resentment at circumstances or people?