Society at large defines an educated person as one who has amassed wisdom. In contrast, the Torah defines an educated individual as one who has integrated his wisdom into the very fiber of his being. In the eyes of the Torah, one begins to educate himself when he "goes against his grain" and chooses to follow his intellect rather than his impulse.
This idea holds true not only with regard to Torah learning, but also with regard to the performance of mitzvos. Many mitzvos are not "natural" actions that would have been otherwise performed if not for the commandment. Laying tefillin, wearing tzitzis, affixing a mezuza, blowing a shofar and shaking a lulav are but a few such examples. The performance of these mitzvos requires a certain amount of subjugation of the body to the mind. One's natural tendency would be not to carry out these deeds and thus their performance requires a person to once again place intellect over impulse.
However, there are mitzvos that seem to work entirely in tandem with our nature. Examples of this type of mitzvah would include eating in general and more specifically eating matzah or the korban Pesach. If the bottom line of avodas Hashem is to get us to go against our grain, how is that accomplished when one performs a mitzvah that is completely normal for his body? Rav Wolbe (Daas Shlomo) explains that these mitzvos also necessitate a struggle against one's natural tendencies.
In explanation of the pasuk at the end of this week's parsha, Chazal tell us, "'And you are to sanctify yourselves' refers to the mayim reshonim - washing one's hands before partaking of bread, 'and you shall become holy' refers to the mayim achronim - washing one's hands after eating" (Brachos 53b). Obviously, the directive to wash mayim achronim was not meant solely as a means of ridding our fingers of salts that may have dangerous properties. Had this been the case, the Torah would not have described this washing as a means of becoming holy. So what indeed lies behind this act of sanctification? The answer offers us valuable instruction on the proper approach to those mitzvos that seem to jive completely with our nature.
The need to sanctify oneself before eating is understandable since eating is a holy endeavor. At the very least it is a fulfillment of the Torah's commandment to guard one's health (Devarim 4:15). On its highest level, ingesting the food on one's table parallels the partaking of korbanos which are brought upon the mizbeiach (see Kesubos 105b). Conversely, eating is also a pleasurable activity which is often arouses one's ta'avah - base desires. We are instructed to wash mayim achronim to cleanse ourselves from the arousal of any such ta'avos.
Chazal are informing us that on the one hand if a person perceives eating as an entirely animalistic instinct, he will never succeed in elevating himself to a level of kedusha since he perceives himself in a very physical manner. On the other hand, if he views eating as an exclusively holy endeavor he will fool himself into thinking that he can indulge to his heart's content, for after all he is involving himself in a most holy pursuit. Thus, it is clear that even those mitzvos which comply with our natural tendencies also necessitate an avodah. We must prepare for them as we would do for something holy, but we must constantly confirm that we are not fooling ourselves into believing that we have already reached the level where the physical actions are purely an expression of the spiritual.
Every time we eat or drink we are afforded an opportunity for avodas Hashem. A small amount of preparation before engaging in these completely natural actions can reap immeasurable reward. When one is cognizant of the fact that that he is about to engage in a mitzvah, and he takes care not to indulge for the sake of indulging, he will succeed in "sanctifying himself and making himself holy!"