Think back upon your life. We all have different motivations (old nature) when deciding whether or not to obey a parent whom we love. Let us look at the following analogy:
Your father (who is a good man and who you respect and love) asks you to mow the lawn on Saturday morning and you really don't feel like doing it. When you fuse and complain and say, "Come on Dad, I had plans today to go to the mall with my freinds. Can I do it next week?" What would most compell you to obey his request:
1) He tells you that if you mow the lawn he will give you the keys to the car Saturday night.
2) He tells you that you will be grounded all weekend if you don't comply.
3) He tells you, "I'm sorry you made plans. However, I am asking you to mow the lawn."
When you love someone who is in authority over you how is that love manifested in your actions, thoughts, motivations, and decisions? Do you get joy out of simply obeying them or do you require something: 1) a personal reward, or 2) to avoid punishment?
I am sure you know where this is going. But, this is very important as we think about the battle between feeding the flesh or obeying the Lord. What is your motivation? Why are you a "good" Christian?