In the "Simplicity" chapter of Richard Foster's "Celebration of Discipline," he states that:
"Freedom from anxiety is characterized by three inner attitudes.
- To receive what we have as a gift from God
- To know that it is God's business, and not ours, to care for what we have
- To have our goods available to others."
He warns against legalism and extremism. Lest we dismiss these as impractical and unrealistic, he explains beautifully that each is tempered with common sense, and discernment - which are, afterall, some of God's good gifts!
Here is a good interview in which Foster explains more of his understanding of Biblical Simplicity.