to be made new in the attitude of your minds;
Here is the second step to true change.
The first step was highlighted in the last verse. The step was to put off the old self. The old self is dominated by those sinful desires, those desires to go against God's way of life, God's way of doing things.
This step is the one that gets missed many times. We know that if the first step is to put off, then the next step is probably going to be to put on, but this middle step cannot be ignored. In order for this process to work, the area of our mind must be handled. The mind (or the heart) is the source of all that we do. If you try to adjust the outward, and let your mind do whatever it wants, eventually that will come out.