Lamentations 3:39

Wherefore doth a living man complain, a man for the punishment of his sins?

The question is why a living man should complain when he is suffering punishment for his own sins, for he has no just cause to complain when affliction comes as the penalty of personal wrongdoing. Complaining, and especially complaining against God, has no place in such suffering, since the penalty exposes departure from truth and righteousness. Affliction of this kind should instead prompt a searching of one's ways, repentance, a return to the Lord, and confession of transgression and rebellion, making suffering a reason for self-examination rather than complaint.

The sinner is treated better than he deserves and remains alive only through mercy, so he has no just cause to complain of hardships received as punishment for sin. The aches, pains, disappointments, and troubles common to fallen humanity should therefore be weighed against guilt and alongside the good things still enjoyed, rather than treated as grounds for complaint. Remembering the punishment deserved for sin, even eternal torment, makes present hardship appear better than one merits and keeps the heart from desponding or repining.

A living person should not complain about light afflictions when others endure severe illness, disability, or mental suffering. While enduring affliction, those who bear the cross have the hope of everlasting peace and glory and the assurance of help. The burden that weighs a person down is not the cross itself but selfishness.