How long does it take to break a negative habit and create a new habit?
All people are creatures of habit. Habit is a reactive system; it is the program we have inside our souls, in our subconscious. As a result, we behave in a certain way, over and over. The habit is a program. The longer we stay with the program, the more we become like robots or animals. Animals never change; they have no freedom of choice. Unlike robots and animals, we have free choice to resist our habits and constantly transform ourselves.
How long does it take to break a habit? It depends on the person. Some people can change overnight. For some people, it could take years. But Kabbalists teach that we should engage ourselves with new habits for forty consecutive days. By doing something new that is not your program for forty consecutive days, you can actually become reprogrammed. Just like installing a new program on a computer, you put a new program in your system, in your subconscious. Our goal in life should always be to change ourselves, not stay in the same habits. Downloading a new program into our system takes forty days.
As Rav Elimelech from Lizansk once said,
“If a person was born with a stubborn nature he should break his nature for forty consecutive days, doing the opposite of what comes naturally to his mind. A person should accustom himself to do every action promptly, be it going to sleep, waking up in the morning, getting dressed and washing hands, clean his body as well as going to the synagogue to pray and so forth…
A person whose speech, because of his nature or his tongue, is not clear or well arranged should accustom himself for forty consecutive days of listening to speeches that are uttered naturally, be it worldly or spiritual matters, or while studying. Know that a habit becomes power that governs. Therefore, if a person's nature is not studious he should accustom himself to study forty consecutive days more than he is used to.”
The number forty is significant; it corresponds to the forty days and nights that Moses spent on Mount Sinai, the forty years the Israelites wondered in the dessert, and the rain that continued for forty days and nights, causing the great flood.
The technology of the number can be broken into two parts: the number four represents the four worlds (Atzilut/Emanation, Beriah/Creation, Yetzirah/Formation, and Asiyah/Action). We also have Ten Sefirot—the ten dimensions or frequencies in the universe. If you take the four worlds and multiply them times the ten frequencies, you get a whole new structure. Therefore, every time you want to create something new in your life, whether breaking an old habit or building a new one, it is best to continue for a process of forty days.