If we understand how the passions are aroused then we can find ways to keep them under control.
Fr. Dimitru Staniloae writes,
In all Orthodox spiritual writings we find the the following sequence as the way in which the passions are aroused in every circumstance:
Satan puts a sinful thought into our mind, the so-called attack... It is the first appearance of the simple thought that we can commit this or that sinful deed. It appears in the mind as a simple possibility. It isn't yet a sin, because we haven't yet taken a position in regard to it. It seems to be outside of us; we didn't create it, and it still has only a theoretical character, a not very serious possibility, which doesn't seem to concern us much. We are preoccupied with our whole being with something else. We don't know where it came from; it seems as though someone were playing and threw it on the side of the road. But we continue to think about it. So it has all the characteristics of a thought discarded by someone else and therefore the holy Fathers attribute it to Satan...Have you ever wondered where some of the thoughts you have come from?
From this attack until the sinful deed we find numerous steps.... The decisive moment is when our thought takes a position. If we have rejected the thought at the first moment, we have escaped. If, however, we start to think about it, to relish the sin in our mind the "coupling" or the mingling of our thoughts with those of wicked demons has already happened. Now we have joined ourselves with the evil thought; it has become part of us.... by it we have entered the area of sin and we can hardly stop the full development of this process once it is set in motion. The assent to the fact follows next, or the plan composed by our thoughts and the thoughts of Satan from the realization of the fact. Only now does the simple thought materialize in images.Have you wondered why to consider some of the thoughts you do consider? One of my favorite passages is one by Saint Paul where he describes his frustration with this issue.
Apostle Paul says,
For what I am doing, I do not understand. For what I will to do, that I do not practice; but what I hate, that I do. If, then, I do what I will not to do, I agree with the law that it is good. But now, it is no longer I who do it, but sin that dwells in me. For I know that in me (that is, in my flesh) nothing good dwells; for to will is present with me, but how to perform what is good I do not find. For the good that I will to do, I do not do; but the evil I will not to do, that I practice. Now if I do what I will not to do, it is no longer I who do it, but sin that dwells in me.
I find then a law, that evil is present with me, the one who wills to do good. For I delight in the law of God according to the inward man. But I see another law in my members, warring against the law of my mind, and bringing me into captivity to the law of sin which is in my members. O wretched man that I am! Who will deliver me from this body of death? I thank God—through Jesus Christ our Lord!
So then, with the mind I myself serve the law of God, but with the flesh the law of sin. (Romans 7:15-25)
The implications of this process are clear. If one wants to progress in the spiritual life we must first have faith and firm reason why these thoughts should be rejected. Rejecting requires a firm stance, a disciplined mind, and the help of God.
Fr Dimitru says,
Therefore the duty imposed on the one who wants to go ahead in his life towards perfection is to watch continually the thoughts which appear in the field of conscience. He must eliminate the thought of any passion at its first appearance. The guarding of the mind, attention, and steadfast, alert resistance to thoughts are continuous recommendations of the spiritual masters for those who doesn't want to fall victim to the passions....It means keep the mind submerged, full of love, in the divine infinite, which enriches it with ever new and pure meanings.
This is the first task of Orthodox Spirituality.
Ref: Orthodox Spirituality, pp 109 - 114.