"The exit from agony is always there. The tunnel out of the agony sector is always in front of you and yet you don't take it. You don't take it by choice. You want to indulge a lot and be in pain. The easiest way out is to write a list of what you're grateful for. If everybody literally did that before they went to bed at night, there'd be no unhappy people."

Next Quote

Both good and evil, when they are full grown, become retrospective...That is what mortals misunderstand. They say of some temporary suffering, 'No future bliss can make up for it,' not knowing that Heaven, once attained, will work backwards and turn even that agony into a glory. And of some sinful pleasure they say 'Let me but have this and I'll take the consequences': little dreaming how damnation will spread back and back into their past and contaminate the pleasure of the sin.

— C. S. Lewis