After describing the downward spiral of "futility thinking," Paul reminds the Ephesians that it is possible to "put off your old self" and be made "new."
What is very striking to me is that Paul centres this life transformation on their knowledge and experience of Christ. New life is knowing Christ and learning from His Truth (the example He set during His Incarnation by being obedient to the Father even by going to the cross.) Being in tune with Christ's life will help us put off the old self and develop a new mind attitude that will lead to a new self.
Trying to live good lives on our own does not work - new life is found in Christ. The more we look at Him, the more we know Him, the more we will become like Him.
It is the "attitude of your minds" that is all-important. If we fill our minds with God's truth and the example of Christ then transformation can take place. It is very much a battle of the mind, not so much the power of positive thinking, but rather the power of the truth of Christ being at the heart of how we think and act.
There is a verse in Acts (4:13) that says it all:
"When they saw the courage of Peter and John and realized that they were unschooled, ordinary men, they were astonished and they took note that these men had been WITH JESUS." (Emphasis mine)