The struggle of Romans 7 illustrates a frustration many Christians feel. They want to do "right" but find themselves doing the very thing that they don't want to do. Then they feel shame, frustration and fear. They are acting as a slave to sin. By trying in their flesh to do better they present themselves as slaves to sin trying to get better. They are starting from the wrong premise. They are actually slaves of righteousness in Christ, new creations not subject to condemnation. When we submit to our new husband (the old law husband has died so we are free now to marry the new) we become slaves of righteousness. We produce fruit in keeping with righteousness and holiness. This doesn't mean we do everything right, we are growing, but we are presenting ourselves and knowing ourselves to be a new creation in Christ, no longer subject to that cycle of sin. It's not a mind game, it is the truth. It is a rest. Starting with the true premise we've been given in Christ, we are free to grow and overcome.