From a 1958 letter to 'Mr. Pitman'--
The great discovery for me was that the attack does not last forever. It is the devil's lie that the only escape from the temptation is through yielding. After prolonged resistance it will go away: what seemed yesterday impossible to turn one's mind from will today be utterly unenchanted, insipid, tedious.
--Collected Letters of C. S. Lewis, 3:920; emphasis original