For who is our hope or joy or crown of exultation? Is it not even you, in the presence of our Lord Jesus at His coming? For you are our glory and joy (1 Thessalonians 2:19-20).
Paul assumed several things concerning the coming of the Lord Jesus Christ. First, he assumed that we will know one another at that time in Heaven. He told believers that when Jesus comes they will be the crowning glory of Paul's ministry. Obviously, he assumed he would know these believers in the future. Not only does he say that he will know them, but also that they are essentially his crown of reward. They are the basis of his boasting or exaltation before God, and they were the basis of his reward from God. What Paul has done for them will be the basis for what God will do for him.
His ministry to believers was based on the joy that he found in them. His was not a boring dry businesslike service, but an emotionally rich relationship of service. Even more so he called the believers he ministered to his glory. Glory is the expression of who we are and who God is. Paul stated that how we treated believers was the expression of who he is. Twice he called believers his joy.
So, in the future we will meet the believers we have ministered to and how we treated them and how we felt about them will be the basis of our reward, our crown.