Rom 5:8; vs Phil 1:29; NET Christ died as our substitute on the cross; we suffer as his substitute now that he is seated at the right hand of the father.

Suffering in the human realm started after the sin of Adam and the woman in the Garden when God put the whole earth under a curse. Gen 3:16-19; Rom 8:20-21;

This means that during this time of probation while we live with old sin nature infused bodies in the devil's' world, suffering acts as a guardian or control in life and as a result plays an important role in the life of all adult human beings. What our parents did for us in childhood, suffering does for us as adults in what is referred to as the school of hard knocks.

God has given us suffering as a parent or control for our lives for our benefit.

2Cor 4:15-18; For all things are for your benefit, that the grace impact which has increased through the agency of the many (invisible heroes) may cause the increase of thanksgiving resulting in the glory of God.

v16 Therefore we do not despair, but though our outer person is decaying, yet our inner person is being renewed day by day.