Charity and Faith

I've been reading C.S. Lewis' Mere Christianity, and came across a very thought-provoking idea when he talked about charity. He said:

"I do not believe one can settle how much we ought to give. I am afraid the only safe rule is to give more than we can spare. In other words, if our expenditure on comforts, luxuries, amusements, etc., is up to the standard common among those with the same income as our own, we are probably giving away too little. If our charities do not at all pinch or hamper us, I should say they are too small. There ought to be things we should like to do and cannot do because our charities expenditure escludes
them. I am speaking now of 'charities' in the common way. Particular cases of distress among your own relatives, friends, neighbours or employees, which God, as it were, forces upon your notice, may demand much more: even to the crippling and endangering of your own position. For many of us the great obstacle to charity lies not in our luxurious living or desire for more money, but in our fear--fear of insecurity."

Am I willing to live like that? I don't know. It would mean relying on God more than ever...and now that I say that it sounds pretty stupid. Relying on God is a GOOD thing! It is amazing to be in that situation...to see Him come through for you in expected and unexpected ways. But can I bring myself to let go?