There is much information available out there on redepmtive suffering. I’ll pass on the little bit of it I know but there’s tons of books and writings on this topic as well. We can look at Christ’s life, particularly His passion, and see how each thorn in His crown, each person walking away from Him - every suffering He endured was out of love for us and to put us right with God. Similarly, we can offer hardships out of love for others and for specific intentions. The hardship you offer up could be something that happens to you, like being physically injured or being emotionally hurt by a friend. I’ve heard of couples offering up the abstinence part of their nfp cycle in reparation for sexual sins and for an increase in the virtue of chastity. Or it could be a mortification you offer up in which you deny yourself something you like, such as no soda for a day, to make a sacrifice for someone or something. The three visionaries of Fatima would often tie a rough, scratchy rope around their waste inside their clothes and offer up the suffering of that for all to repent, know and love God. I think the part of offering up your suffering to God means you’re praying to make this your offering and prayer for a specific intention, and then being reminded of why you’re suffering and thinking and praying during the suffering (easier said than done). Hope that makes sense and helps a little. God bless!