the dangers of middle-age

(Screwtape urges his nephew to do his best to keep his human patient alive, because time is a great ally to their work...)

The long, dull, monotonous years of middle-age are excellent campaigning weather. You see, it is so hard for these creatures to persevere. The routine of adversity, the gradual decay of youthful loves and youthful hopes, the quiet despair (hardly felt as pain) of ever overcoming the chronic temptations with which we have again and again defeated them, the drabness which we create in their lives and the inarticulate resentment with which we teach them to respond to it - all this provides admirable opportunities of wearing out a soul by attrition.

C S Lewis, The Screwtape Letters, p.155