The result of this approach is twofold. On the one hand, it provides us with a certain peacefulness, clearing the way for better Avodas Hashem. On the other hand, viewing life with this perspective will lead us to a constant sense of urgency to perfect our deeds and thoughts and to a life of repentance and closeness to Hashem. Chazal say, "וְעַתָּה אִם שָׁמוֹעַ תִּשְׁמְעוּ," the use (in the Torah) of the phrase "and now" indicates an opportunity for repentance. (בראשית רבה כא ו)
By living in the present moment, one becomes more mindful of their actions and is able to reflect on their deeds immediately. This introspection helps us ensure that we are fulfilling our duties to the best way possible. Therefore, the phrase "and now" serves as an indication of teshuvah, which is achieved through constant focus on the present.
In the Mishnah, Rabbi Eliezer teaches us that, "וְשׁוּב יוֹם אֶחָד לִפְנֵי מִיתָתָךְ," repent one day before your death (אבות פ"ב י). The Gemara relates (שבת קנג ע"א) that Rabbi Eliezer's students were perplexed by his teaching, since no one can predict the exact day of their death. Rabbi Eliezer clarified that this uncertainty is precisely what he meant. He suggested that if we consider every day as if it were our last day, we will be more likely to utilise it and take greater responsibility over our actions. This, in turn, will ensure that we are in a constant state of repentance throughout our entire life.
According to this Gemara, the Polna'er Rav explained the wise words of Shlomo Hamelech "יִרְאַת ה' תּוֹסִיף יָמִים וּשְׁנוֹת רְשָׁעִים תִּקְצֹרְנָה," The fear of Hashem will increase days, but the years of the wicked shall be shortened (משלי י כז). The Meforshim ask, why does the possuk mention an increase of days for the God-fearing, while the Resha'im are cursed with a shortening of years?
According to the aforementioned Gemara, the answer is clear. Tzadikim live every day as if it were their last, constantly aware of the fleeting nature of life. They embrace each day and strive to fill it with Torah and Ma'asim Tovim. This approach also leads them to perform each day to the best of their ability.
The wicked, on the other hand, feel secure in their long lifespan and tend to procrastinate in fulfilling their duties. They assume they have plenty of time to correct their wrongdoings, and as a result, do not put in the same effort as the righteous to make the most of each day.
But the outcome, says Shlomo Hamelech, is just the opposite. The Tzadikim, who count their days, are blessed with long lives due to their righteousness. Yet, for the reshaim the "years of the wicked", meaning their trust in their long life, curtails their years. It dissuades them from doing teshuvah daily, ultimately shortening their days.
(בן פורת יוסף וישב ד"ה ולמען)