Please turn over to II Corinthians 1, verse 5. Because we share in Christ's sufferings, we also share in the comfort God provides that helps us endure such suffering.
So Paul knew that to share Christ's sufferings always involved God's consolation through that suffering, and he hoped that this would give the Corinthians the boost they needed to triumph in their time of trial. And what he is also explaining there is by the apostles' consolation and sufferings, the laymen - the people, God's people - saw those, and it encouraged them to be the same, to have consolation and salvation through Christ. So by our example of being positive and encouraging, it spreads to the rest of the congregation, the rest of our fellow brethren.
Please turn to II Thessalonians 2, verse 13. Whenever Jesus Christ's sufferings are multiplied, so is His comfort multiplied in us. The greater we suffer for Christ, the greater the comfort we receive from Christ and the greater our ability to share suffering and consolation with others in God's church.