Brothers and sisters: I rejoice in my sufferings for your sake, and in my flesh I am filling up what is lacking in the afflictions of Christ on behalf of his Body, which is the Church. (Col 1:24-2:3)
https://bible.usccb.org/bible/readings/091123.cfm
There is a mystery to human suffering which we may never fully understand. But when we are able to join our suffering to the Sufferings of Christ for the sake of our brothers and sisters, then our suffering takes on a divine dimension and offers us a unique communion with Christ. Some of us remember where we were when we heard of the attacks of September 11. I was on retreat at my seminary. While the events were still unfolding we gathered in the Seminary Chapel and celebrated Mass and prayed for peace.