Usually, if a person is faced with a challenge, the strategy to overcome it is by working hard to get it under control. However, in this area, such a strategy will not work. In fact, the opposite is true: When a person tries to control a thought, he is essentially bringing to mind the very topic that he was trying to rid himself of, which causes his mind to explore it further. For example, if someone tells himself not to think about an elephant, then just mentioning those words will bring the image of an elephant to mind. This idea holds true both with regards to inappropriate thoughts, as well as improper sights.
A person should always remember the Golden Rule: Any time you think about not thinking or seeing it, then “it” is already in your mind. The following anecdote illustrates this idea:
There was once a man who was extremely careful with shemiras einayim. Whenever he went outside, he would look at the ground, so as not to inadvertently see a woman. Everything went fine and well for this individual, until the inevitable happened. To his dismay, the man inadvertently bumped into a... street pole! He immediately ran to his Rebbe with a worried look on his face and exclaimed, “Rebbe, I’m trying so hard not to look at anything I shouldn’t, and now I’ve just bumped into a woman!” The Rebbe responded, “I don’t understand. For my entire life, I’ve been trying to train myself that if I ever bump into a woman, I should think that it’s a pole. And you’ve turned every pole into a woman?!”
How, then, should one deal with inappropriate thoughts and sights? They should be treated as if they are a bag of garbage, waiting for the garbage collector to come. Just as you wouldn’t open the garbage bag to investigate if there’s something good there, so, too, a person should work on himself to consider these thoughts and sights as if they are nothing and just continue on his way. The focus should be to continue on with ‘business as usual’ without even analyzing what just happened.