When we talk about addiction as a disease of the person, there are three distinct areas that are effected: the Spirit, which is darkened and clouded to the point where it does not see God; the Soul, which which experiences this darkness as fear and drives the human person to sin; and the Body, which derives consolation from sin through physical dependency on what the soul indulges in (in the case of chemical dependency, this is usually expressed as an 'allergy' or unusual reaction).
These three factors come together to form the human will, the decision-making aspect of human awareness.
St. Maximos the Confessor describes two kinds of 'wills,' one 'natural' and the other 'gnomic.' Some people interpret St. Maximos as advocating man having two wills, but if you think about it, that would be impossible unless man was made that way to begin with, which is troubling when you think about it. The gnomic will is the fallen one, the one that rushes to judgment without all of the necessary information and becomes captive to the passions, while the natural will waits for all of the information (especially God's light) and makes decisions according to what is right (i.e. what is according to God's divine will).
Natural and gnomic are just adjectives for either a healed will operating according to God's will, or in the case of the gnomic will, it makes decisions based on bad information.
You could say that the gnomic will has 'impulse control problems' and reacts according to deep fears rather than all of the available information. This is why the more severe the addiction becomes, the more the brain's impulse control center appears to deteriorate and the addict finds it harder and harder to act naturally.
Our true natural, thus our natural will, is to do good, but the cutting off of our perception of God leaves us with a gnomic will, which acts according to fear. The healing of the will, thus the removal of the 'gnomic' or 'guessing' action of the will is critical to our healing from addiction.
The problem arises when we ask ourselves, 'How does a broken will will itself into stopping this brokenness?'
We cannot will ourselves into healing our wills, which is the problem of modern psychology when it excludes God. The patient is expected to will himself into health by better using his will, but what can one do when the will is no longer able to distinguish right from wrong?
The Orthodox Church, and later in the 12 Steps, begins with the idea of surrender. We must stop willing and repent, which is the acknowledgement of this gnomic condition of the will and its brokenness. Once we are able to stop willing and reflect on our fears, we see that willing no longer works without God.
The addict, and every human being for that matter, must have the light of Christ in order to see the world properly and make the right decisions. As we allow this light to heal us and repair the will, it will start working in a natural way. We will make the right decisions because these decisions will have God's input.
What the person with a broken will must do is repent and wallow God an opportunity. This takes time, because, as mentioned before, the impulse control aspect of the person is damaged and he jumps into action before having all the information. This is the struggle of sobriety.
It is hard at first to have patience, and this can only begin with surrender of the will to God and the guidance of others who are more spiritually-developed. Thus, we have the foundations of spiritual guidance in the Church and the sponsor in the 12 Steps.
In conclusion, we only have one will, but it can act in two distinct ways. We must always ask ourselves: am I acting according to God's will, or am I jumping to conclusions? That's the key to the 'two wills.'