Paul probably wrote 2 Thessalonians because some of what he said in 1 Thessalonians had been misunderstood. Here Paul gives some harsh instructions for people who claim to be Christians but live lives that even those outside the church would see as evil.
Paul encourages people to follow his example. It’s amazing that he is so confident in his own lifestyle that he wants people follow it. Do you have this level of confidence in your lifestyle? In what areas would you not want people to follow your example?