Saint Theophan says,
"Attentively follow the course of affairs and watch what thoughts accompany them and conclude them, in order later to judge by this what initially lay within."Think of being in a boxing match. In the boxing ring you have to defend yourself from the punches of your opponent. You receive many little jabs that have no direct impact. But these small punches only set you up for that big punch which can knock you out.
Saint Theophan says,
"The enemy has a law––not to begin suddenly with a passion but with a thought, and to repeat the thought often."These repeated thoughts may not always be bad thoughts. The bad ones are easy to reject, but others require keen discernment. When new thoughts come about be wary. Don't immediately incline to accept them. Be patient. Watch and objectively reflect. Don't trust in your own reasoning but share new thoughts with a trusted friend or your spiritual father.
The risk is disillusion. Saint Theophan describes it this way.
"Their foremost characteristic is that a person assuredly considers himself to be something he is not––for example, call to teach others, capable of an extraordinary life, ad so on Our pride is always lurking in the back ground waiting to be satisfied."Our challenge is to free our mind of unnecessary thoughts. Saint Theophan states,
"The result of warfare can be a mind free of thoughts, a heart free of passions, and a will free of tendencies. When this develops, the person has achieved passionlessness. His inner being becomes a clear mirror that reflects spiritual things."