"They traveled three days in the wilderness and found no water." -Exodus 15:22
Midrash Tanhuma, Parashat B'shallah, 15
Some are of the opinion that, up to this point, the Israelites still had drinking water that was given to them as they crossed the Reed Sea, which was now used up. What is then the meaning of "and they did not find water"? They did not find water in their containers, as was stated: "Their officers send out their youngsters for water. They go to the reservoir, but do not find water; they return with empty containers; they are embarrassed and ashamed and cover their heads" (Jer. 14:3). The expounders of Scripture explain that they absented themselves three days from Torah study, which is compared to water, as it is written: "Ho! Everyone who is thirsty, go to the water" (Jer. 55:1). Therefore, the prophets and the Sages ordained that the Torah must be publicly read on three days each week. It is to be read on Shabbat, on Monday, and on Thursday, and thus there is never a lapse of three days without Torah.
"And he said, 'If you vigilantly obey the voice of Hashem, your God'" (Exod. 15:26). Because of this repetition (shamoa tishma), the Sages said:
When a person wants to obey a command at the proper time, he will be given the opportunity to obey additional commands as well; however, if he wants to forget [a command when it is given to him,] he will be made to forget additional commands as well, as it states, "And it will be, if you vigilantly obey [shamoah tishm'u] [My commandments which I command you this day . . . "]. (Deut. 11:13)
It is said that a habit takes three weeks to make and three weeks to break, and one thing on which the self-help gurus agree is that consistency matters. So here we have it, a midrashic bit of self-help advice: don't go more than three days without learning Torah (substitute here the worthy bit of self-improvement of your choice), and know that once you begin it will get easier. If you let yourself slip, well, it's downhill all the way.
The question, then, is the sort of habits we'd like to undertake. For what does our soul yearn, for what do we thirst? Those of us reading this far down into the weekly Torah from JTS email have some sort of commitment to Torah learning in common; the Sages' reading of "thirst" as "Torah study" might appeal. I wonder though—if we open up the midrash, what else do we find ourselves thirsty for? The question is answered so quickly after it is posed in the text above—indeed, the question is not even posed, it is taken for granted and the "expounders of Scripture" give it all away. But lingering is the unasked question lying just beneath the surface: for what did the Israelites thirst as they wandered through the desert, having left home for an unknown place? And as we see ourselves undertaking a form of that same journey in our own lives, for what do we thirst and what do we need to do to quench our yearnings?