Still reading John Bevere's book... the lessons are rather hard to take.
A servant obeys, but not always willingly. He may be unhappy in his heart with what he has been asked to do, he may not always be able to understand the will of his Master, but he obeys because he understands that obedience is non-negotiable.
A friend understands the heart and innermost desires of the Master. He does what the Master asks with great joy and without hesitation, and desires what the Master desires.
Taking the analogy a step down, a parasite or thief lives off the generosity of the master. He neither obeys nor recognises the authority of the Master of the house, but in spite of this stridently claims food and board as his right.
I obey, but not always joyfully. The fear of the Lord is helping me to keep His commands. But how does one move from servant to friend?
Covetousness is the root of much sin. Covetousness tells God that He isn't doing His job properly, that you could do a better job than He, and that your own personal needs are more important to you than your relationship with Him. The Israelites were unhappy with how the Lord had been sustaining them. Balaam always questioned the Lord's commands. Covetousness is like the sin of idolatry (Eph 5:5 I think)