2 Corinthians 4:16-18

(16) Therefore we do not lose heart. Though outwardly we are wasting away, yet inwardly we are being renewed day by day. (17) For our light and momentary troubles are achieving for us an eternal glory that far outweighs them all. (18) So we fix our eyes not on what is seen, but on what is unseen. For what is seen is temporary, but what is unseen is eternal. 

From the day we are born, the process of aging begins. First it lifts us up to strong adulthood, then it starts to decay us as we grow old. During this journey, we face many trials that can speed up the process of decline. It doesn't matter if you are born of royalty or a pauper, you will face your own form of tribulations that will cause worry and test your limits. 

But what Paul is saying in his second epistle to the Corinthian church is that whatever troubles we face that causes us to wither physically, is actually strengthening us spiritually. As this world tears us apart day by day, through our faith in GOD, it also builds us up internally or spiritually and conditions us to enter into eternity with a strong and healthy spirit.

GOD is not cuel. HE is the exact opposite of curel. HE is love and through HIS love, we can take heart that all the seemingly endless troubles we face in this life are mearly exercises that will make us invincible spiritually.