Note the present tense of this verb, indicating that such suffering is ongoing as opposed to limited to a short while. The verb the apostle uses means to accomplish, bring to completion.
The point is that God himself has ordained the battle of Genesis 3:15 with its accompanying suffering (“bruise his heel”) and so each person on the side of the Seed of the woman invariably must undergo suffering according to God’s ordinance, and complete it. See also 1 Peter 1:6.
9 Resist him, firm in your faith, knowing that the same kinds of suffering are being experienced by your brotherhood throughout the world.