Paul shows us that the works of the flesh are just as much attitudes as they are actions. Both are just as much over-desires of our flesh. 

Paul begins the works of the flesh beginning with sexuality. Sexual immorality is defined as sexual intercourse between unmarried people. Then he moves on to impurity referring to unnatural sexual practices and relationships. He ends the sexuality section with sensuality in reference to uncontrolled sexuality. 

In verse 20 Paul enters into works of the flesh in reference to religion with idolatry and sorcery. He is referring to specific occult and pagan religious practices. The first is providing an inadequate substitute for God, and the second is faking the work of the Spirit. 

Paul follows that with eight words about how the flesh destroys relationships. Four of the words are destructive attitudes: rivalries, jealousy, enmity, and envy. The other four words describe the results of these attitudes: strife, fits of anger, dissensions, and divisions. 

Paul ends his specific list with drunkenness and orgies showing us that one of the works of the flesh is an addiction to pleasure-creating substances and behavior. 

Paul ends with a warning about this list. Paul refers to the habitual practice, rather than infrequent and repented-of lapses. He is referring to someone who continually indulges the sinful nature without battling against it. This shows that the Son has not redeemed them and that the Spirit has not renewed them. Paul is not looking to undermine our Christian assurance here, he is just trying to help us destroy our sense of complacency.