I thank my God in all my remembrance of you, (ESV)
When Paul thought about Philippi he thought of the people. And thinking of the people of Philippi made him thankful. When you think about what happened when Paul was first at Philippi it might be surprising that he thinks of the people and not what happened to him at the hands of the Romans Empire. Let's remember together what Paul had previously experienced at Philippi:
 The crowd joined in attacking them, and the magistrates tore the garments off them and gave orders to beat them with rods.  And when they had inflicted many blows upon them, they threw them into prison, ordering the jailer to keep them safely.  Having received this order, he put them into the inner prison and fastened their feet in the stocks. (ESV)
Paul had delivered a slave girl from demonic possession. His reward? He was beaten and thrown into prison. I am sure that Paul had not forgotten his unjust treatment. His memory still worked. He knew that those rods had brought much damage to his body. I am sure that some of the pain of those blows lingered the rest of his life. But Paul chose to remember the godly people of Philippi, not the injustice.
I think that there is a lesson here for us. We are often so overly sensitive about how we are treated that we forget to focus on the people who have been a blessing to us, and that we have had the privilege of knowing. Paul was thankful when he thought of Philippi. He knew that in the grand scheme of things people are more important than injustices.
Have you been treated unjustly? Give that hurt to the Lord. Allow him to show you how he is working in the midst of that tragedy. Look for the people in the situation who you can be a blessing to. If you do you will be able to look back with thanksgiving.