In today's world everything happens fast, real fast. To speak to someone, no landline is needed - just pick up the cell and there he is. To speak "in per-son," just "Skype." And to communicate in writing, just text, and don't even bother paying any attention to the spelling.
It is not just fast; it is just about immediate.
So are the nisyonos. One need not "prepare" to do something wrong. No forethought or planning is required. As soon as the impulse hits, the aveirah is right there, at your fingertips, literally.
How does one fight such a battle? By inculcating himself beforehand with a host of images and arguments that conjure up for him the dangers involved in failing and the reward to be enjoyed by overcoming the challenge.
The following excerpt from the Chofetz Chaim (Nidchei Yisrael Ch. 23) provides such an image:
It is found in the sefarim that one who overcomes the yetzer hara for arayos is granted a beam of light that shines over his head - a light that was actually visible at the times of Chazal!
While that image may be difficult to envision, the Chofetz Chaim continues with something that provides us with another image that we can easily relate to:
Realize also that one who overcomes his yetzer, especially in today's times, for the sake of honoring Hashem, will certainly merit an exalted level in Olam Haba... and will merit even in this world, that he and his children will be among the mighty people of Klal Yisrael, always doing what is cor- rect and just ...
That is, by being vigilant in inyanei arayos, one merits that not only he, but all his descendants until the end of time, will carry on his courageousness and strength of character, and will be predisposed to do what is "good and just."
Burn this image into your consciousness:
You have an impulse to do an aveirah.
Standing behind you are your dear children - your sons, of whom you are so concerned that they learn and grow in their yeshivos; your daughters, for whom you desire that they remain modest, marry well, and build wonderful Jewish homes. But that is not all.
Standing behind your children are their children, and behind them as far as your eye can see - spreading like an eagle's wings - are the exponentially increasing number of your descendants. They are all watching you, holding their breath, waiting to see what you will do, whether you will elevate their lives by resisting the temptation, or whether you will succumb to the blandishments of the moment.