Forming healthy habits is an integral part of life, and of course the more consistent we are with our behavior, the more habitual it becomes. Under normal circumstances, you can’t expect to be good at something by just doing it once; and you also can’t expect to retain a skill you’ve already acquired without continued practice.
That said, since no two people are alike, what it takes to form a habit will vary from person to person. While one person might need a year to get good at something, for someone else a month will do. Where one person requires extreme repetition, over and over and over, another person can get away with doing it once and owning it.
Obviously, even someone that requires less time and work to master something still needs to keep at the task in order to allow it to become his second nature. He may be able to get good at it quickly, but if he doesn’t consistently perform the task, it will become just another thing he’s good at but of little actual significance to his life.
This concept applies to all areas of life, but it especially applies to our commitment to Torah and Judaism. Steady and consistent observance are needed in order to master the fulfillment of mitzvahs, and the longer we’re at it, the better we get.
That being the case, some might ask, why the focus on the one-time performance of a single mitzvah? If consistency and perseverance are fundamental, why is so much emphasis placed on doing a single mitzvah? Shouldn’t the focus be instead of repetition and habit-forming activities?
The truth is that both can be correct. Focusing on forming healthy Jewish habits is certainly necessary for a well-rounded Jewish life. Yet at the same time, there is immense value in the performance of a single mitzvah. And not only are these two paths not contradictory, they complement each other.
When a Jew devotes himself to the performance of a single mitzvah without self-interests or ulterior motives, he just does it because he knows it’s the right thing to do, the Torah promises that “there will be no bereaved or barren in your land.” In addition to this being a clear blessing for prosperity and health as a result of adhering to Torah, it also directly relates to the effect of the mitzvah itself.
One might be concerned with the benefits of doing a mitzvah as a one-off, since it will seemingly not lead to any future spiritual growth. What good is there in putting on tefillin once if I will never do it again? Why should I go to the mikveh if I don’t plan on doing so regularly? So G-d informs us that not only is a one-time mitzvah not a waste of time, but it can actually have long lasting effects both on the person performing the mitzvah and on the world around him.
“There will be no bereaved” means that the momentary inspiration felt during the performance of the mitzvah will not be lost down the line; and “no barren” means that even a brief singular act will bear fruits and will certainly not be wasted.
The phenomenal blessing behind these words ensures that there will certainly be future mitzvahs, that this one mitzvah will be all we need to create a habit of connecting with G-d regularly through even more mitzvahs. So while some people need a lot of repetition to get good at something, G-d tells us that doing even one mitzvah just once is really all a Jew needs to turn his life around in the most consistent way possible.