Quaker educator Parker Palmer writes that we can only give away what is truly ours. He writes this in the context of our "calling," that we can only serve in ways that we are gifted to serve, and that trying to give what we "should" and serve as we "ought" can damage ourselves and the recipients.
But perhaps his idea applies to possessions, as well. Stuff has a way of owning us instead of the other way around. I find that I can let my fear of not having what I am used to be more powerful that the joy I experience in "having" or in giving away. Maybe this widow could give all she had not because she didn't need it -- she certainly did -- but because she knew her coins did not define her, and that she controlled them and not vice versa.