Rav Wolbe notes that a person who is interested in getting to know himself, must be aware of one more concept. As was mentioned, most often it is a person's imagination which leads him to sin. After fantasizing about the pleasure that an action will presumably bring him, he follows his illusion and commits an aveirah.
However, sometimes it seems that an aveirah strikes without any prior warning. For example, a person might simply be shmoozing and the next thing he knows he is speaking lashon hara. Acting out of anger is another example of such a phenomenon. Generally, lashon hara and anger are not specifically pleasurable and thusly they are rarely prefaced by one fantasizing about such behavior. This being the case, what brings a person to commit these sins?
Chazal tell us that such behavior is an outcome of the dominion given to the yetzer hara. "Should a person's anger bring him to tear his clothing, breaks vessels or throws away his money; such behavior should be perceived in your eyes as if he has worshipped idols. For this is the method of the yetzer hara. Today he says do this and tomorrow he says do that, until he succeeds in bringing a person to idol worship" (Shabbos 105b). The yetzer hara is that Pied Piper who has that uncanny ability to get people to follow him blindly, even when there is no significant amount of pleasure in it for them.
The yetzer hara was given this dominion for the simple reason of enabling the world to run as Hashem sees fit. We were put into this world to earn reward by navigating through life without falling into any pitfalls. This can only be accomplished if the world is set up in such a way where we must choose between good and evil. Accordingly, the yetzer hara was created for the sole purpose of digging pits to entrap people. He has been given great dominion, and he even can offer us pleasures, but he cannot provide lasting happiness.
The Gemara (Sanhedrin 91b) describes just how controlling he is. Antoninus asked Rebbi (Rebbi Yehuda HaNasi) at what point the yetzer hara exerts control on a person. Rebbi responded that the yetzer hara already exists from the time of conception. Antoninus replied that if this were the case then the fetus would "kick his mother" and leave her womb; i.e. the yetzer hara would force the baby into the world prematurely thereby causing its death. Rather, it enters the body at the time of birth. This sums up the influence of the yetzer hara: He cruelly pushes a person to perform actions that ultimately wreak havoc upon himself.
Yet, we know that Hashem established the world in a manner that good mirrors evil (zeh l'umas z'eh asah HaElokim). If such a powerful negative force exists, there must be a similar positive force; one that has the ability to propel a person to take action which will ultimately bring upon him blessing and goodness. This force is known as yiras shamayim. It is the force which invariably prompts a person to fulfill his obligations and to take necessary precautions.
The summer vacation is a litmus test of sorts which can gauge a person's yiras shamayim. Is he merely seeking to get away and have a good time or is he thinking beyond enjoying the fleeting pleasures of vacation? Does he take the proper precautions before choosing a destination? Does he pack a sefer inside his suitcase? We must bear in mind that we strive not for superficial pleasures but for true and lasting happiness!