We are creatures of habit. We tend to do what we have done in the past, which is why it is so important to get things right the first time. Learn it wrong initially, and the mistakes can stay with you a lifetime. Practice does not make perfect. It is proper practice that makes perfect, practice only helps to form our habits. 
This explains why the mitzva of chinuch, educating our children, applies only when a child can do the mitzva properly and in its entirety. Even though one fulfills the mitzva of lulav just by picking it up, the mitzva of chinuch does not apply until the child knows how and when the lulav should be waved. That is easier said than done and the proper waving of the lulav was a matter of Tannatic dispute. Needless to say giving a child a non-kosher lulav is not only meaningless but may actually do more harm than good. Teaching children bad habits can have far reaching implications. It is for this same reason that Kiddush is not made in shul on Yom Kippur and the wine given to a minor to drink. We do not want a child associating the mitzva of Kiddush with eating on Yom Kippur. 
This principle has moral implications as well. “As Rav Huna said, when one commits a sin and then repeats it, it becomes for him permissible.” (Kiddushin 40a) The Gemara is rather startled by this claim - is it really permissible? - and explains that Rav Huna meant that “it becomes permitted to him.” Once someone is habituated to a certain practice, good or bad, it becomes part and parcel of what we do naturally. We surely no longer view it as sinful.
But more than the power of repetition our Sages were emphasizing what is known in psychological literature as cognitive dissonance. Acting in a way that contradicts the way we believe creates internal tension and leads one to act  in a way to reduce that tension.
As it is much easier to change our belief system than our actions we will typically shape our beliefs to conform to our actions thereby eliminating the cognitive dissonance. 
To knowingly act in a way that is sinful is not easy. We like to belief that we are good people and that our actions reflect correct behaviour. We can acknowledge the occasional failing but to admit our routine practices are wrong is not something we can readily due. As Rav Huna notes the likely response is to say that we are not sinning; that “it is permissible for us.” Instead of changing how we act we are much more likely to justify our actions. The ba’alei mussar[1], the great ethicists of our tradition, took Rav Huna’s teaching a step further and wondered what happened when the sin is repeated a “third” time. Not only does the act move from being sinful to permissible it then moves from being permissible to becoming a mitzva, an action we must do. How often have we witnessed an act, which to the objective observer is so obviously wrong, be a rallying charge of action for the subjective actor involved? 
So powerful is our ability for justification, that Ulla uses this principal of Rav Huna in asserting that even thinking about sinning can already counted as sinful. While we noted in our last post that, with the exception of idolatry, our negative thoughts are not held against us, Ulla apparently disagrees. Once one has become habituated to a certain sin thinking about that sin is the first step in repeating it. After all it is no longer sinful. And in a rather depressing thought Rashi notes that even if the person does not continue to sin it is not because he considers the action wrong but rather he no longer has any interest in the sin[2].
It is this concept that forms the basis of the Sefer Hachinuch the classic listing of the 613 mitzvot. It is regarding the mitzva of korban pesach where the anonymous author explains that the Torah commands the performance of so many mitzvot because actions mold character. 
And there is no aspect of Judaism that involves more activity than Pesach. All that activity before, during and even after that makes Pesach so impactful. Is it any wonder that it is the most widely observed ritual? Even many who practice little else observe at least parts of Passover. 
Thankfully habits works both ways. When one is in the habit of performing mitzvot they too become second nature. 
Pesach offers so many opportunities to get into some great habits. Maot chitim, learning, teaching, spending time with family, davening, simcha are all ideas that with enough practice can become second nature. Let us make sure we properly practice them.
[1] This term generally refers to the disciples of Rav Yisrael Salanter (and his students) the 19th century founder of what is known as the Mussar movement. Focusing on ethical improvement these masters used their tremendous insights into human psychology to teach how we can develop our character most positively. I do not think it is coincidental that the “flourishing” of the mussar movement and modern psychology happened at approximately the same time.
[2] If you ask what about teshuva, yes it is possible but not very likely. Our Sages were great realists. They extolled the greatness of teshuva precisely because it is so difficult. It is important to recall the Talmudic understanding of a ba'al teshuva was a religious person who sinned or more powerfully had a character flaw that they worked very very hard to rectify. Success was not a given. The notion of a person brought up wihtou observance becoming shomer Shabbat was unknown to our Sages. The ideal ba’al teshuva was one who perfected his character (see Ramban, Hilchot Teshuva, chapter 7).