The problem about avoiding our own pain admits a similar solution. Some ascetics have used self-torture. As a layman, I offer no opinion on the prudence of such a regimen; but I insist that, whatever its merits, self-torture is quite a different thing from tribulation sent by God. Everyone knows that fasting is a different experience from missing your dinner by accident or through poverty. Fasting asserts the will against the appetite—the reward being self-mastery and the danger pride: involuntary hunger subjects appetites and will together to the Divine will, furnishing an occasion for submission and exposing us to the danger of rebellion. But the redemptive effect of suffering lies chiefly in its tendency to reduce the rebel will. Ascetic practices, which in themselves strengthen the will, are only useful in so far as they enable the will to put its own house (the passions) in order, as a preparation for offering the whole man to God. They are necessary as a means; as an end, they would be abominable, for in substituting will for appetite and there stopping, they would merely exchange the animal self for the diabolical self.
From The Problem of Pain
Compiled in Words to Live By
The Problem of Pain. Copyright © 1940, C. S. Lewis Pte. Ltd. Copyright restored © 1996 by C. S. Lewis Pte. Ltd. All rights reserved. Used with permission of HarperCollins Publishers. Words to Live By: A Guide for the Merely Christian. Copyright © 2007 by C. S. Lewis Pte. Ltd. All rights reserved. Used with permission of HarperCollins Publishers.