Our Gemara on Amud Aleph mentions a hermeneutical principle that also is used metaphorically:

תָּפַשְׂתָּ מְרוּבֶּה לֹא תָּפַשְׂתָּ תָּפַשְׂתָּ מוּעָט תָּפַשְׂתָּ

If you grasped too much, you did not grasp anything; if you grasped a smaller amount, then you grasped something.

In the hermeneutical sense, if there is an equal interpretive option to derive from a verse a larger quantity or a smaller quantity, you derive the smaller amount. This is because the smaller amount is still within the bounds of the larger, so if you choose the conservative estimate you are at least accomplishing a portion that even the larger amount implies.  But if you choose the larger amount, you might overstep the bounds and it would be false.  Rashi gives an example of owing money. If the Beis Din rules that the man owes $100 out of a questionable $200, then at least the ruling is partially correct.  But if the judge rules $200, he may be actively and incorrectly taking money away from someone to whom it belongs. 

However, this rule is also used as an aphorism.  If you try to bite off too much at once, you will end up failing.  This corresponds with what we have been discussing the past few days regarding perfectionism, high standards and inability to tolerate failure.

There is another positive aspect behind setting smaller goals.  The fuel and motivation for what we will do tomorrow comes from a sense of success and accomplishment about what we did today.  If you set goals too high, or devalue smaller accomplishments, you starve your internal reward system of a sense of satisfaction.  This is what researchers Teresa M. Amabile and Steven J. Kramer call the “Progress Principle”:

Of all the things that can boost emotions, motivation, and perceptions during a workday, the single most important is making progress in meaningful work. And the more frequently people experience that sense of progress, the more likely they are to be creatively productive in the long run. Whether they are trying to solve a major scientific mystery or simply produce a high-quality product or service, everyday progress—even a small win—can make all the difference in how they feel and perform.

In relation to this idea, Amabile and Kramer discuss the managers who “check in” versus “checking up”.  The latter is testing, probing, micro-managing and finding fault.  The former is a friendly visit to note areas of progress, show support and, if need be, remove toxic bureaucratic barriers that impede success. In parenting as well, these concepts can be applied in a similar way.  Goals should not be too big in order to allow for a daily sense of success, meaning and accomplishments.  Following up on a child’s work should feel like checking in instead of checking up.

Source: https://hbr.org/2011/05/the-power-of-small-wins