We should offer up our sufferings, united with Jesus Christ, to God Our Heavenly Father.
I once asked someone, what do you think, when you have a headache and I say to you, "Offer it up". The person responded, "That you have no pity for me."
Many of us have grown up with the phrase, "Offer it up", without an explanation of what it means. Then it becomes a trite phrase showing no pity.
Catherine of Siena was a mystic and when she was in ecstasy, she would speak aloud what the Eternal Truth was saying to her, and secretaries would write down her words. The book "Dialogue" was written in 1377-1378 and the first chapter tells what it means to "offer it up". All the suffering one endures within a person's life time is not enough to punish one for the smallest sin, for a sin is an offense against the infinite Good, and demands infinite satisfaction. Not all suffering is given for punishment, but rather for correction, to chastise the child who offends. True contrition and sorrow for sin can make satisfaction, but not by virtue of any suffering we may bear, but by virtue of one's infinite desire.
Only God has infinite love and infinite sorrow. The sorrow God wills us to have is twofold: for the offense we have committed against our Creator and for the offense we see our neighbor commit. Those united with God grieve when they sin or they see others sinning.
St. Paul taught: "If I had an angelic tongue, knew the future, gave what is mine to the poor, and gave my body to be burned, but did not have charity, it would be worth nothing to me." [1 Co. 13:1-3]
Gentle Truth said: "...In this life, guilt is not atoned for by any suffering simply as suffering, but rather by suffering borne with desire, love and contrition of heart. The value is not in the suffering but in the soul's desire. Likewise, neither desire nor any other virtue has value or life except through my only-begotten Son, Christ crucified, since the soul has drawn love from him and in virtue follows his footsteps. In this way, and in no other is suffering of value."
Suffering satisfies for sin through knowledge of God's goodness and from contrition and sorrow that the heart finds in the knowledge of itself and its own sins.
One must have heartfelt contrition, love for true patience, and that true humility which considers oneself worth of punishment and unworthy of reward, and thus suffer with patience and so make atonement.