The Torah records two Pesukim that beckon a question, “Re’eih Natati Lefanecha HaYom Et HaChayim VeEt HaMavet VeEt HaRa,” “See, I have placed before you today the life and the good and the death and the evil” (Devarim 30:15), and “UVacharta BaChayim LeMaan Tichyeh Atah VeZarecha,” “And you shall choose life so that you and your children will live” (30:19). Why does the Torah give us a reason to do the Mitzvot and choose “good?” Rav Moshe Feinstein explains that the Torah is teaching not only to do good deeds, but to do a certain type of “good” - when the performance of the Mitzvah is powerful enough to have a lasting effect on that person’s children and impart a love of Mitzvot unto them. For instance, an observant Jew who performs all the Mitzvot but lacks enthusiasm is not doing the good that the Torah tells us to do here, in Parashat Nitzavim. Such a person is showing that being a Jew is a burden and his children, picking up on these vibes, will also lack enthusiasm for the Mitzvot they perform. Conversely, one who shows his great care and love for the Mitzvot by doing them happily imparts this attitude onto the children. This attitude is what the Torah means when it says “good.” Along the same lines David HaMelech teaches us, “Ivdu Et Hashem BeSimchah,” “Serve Hashem happily” (Tehillim 100). Seemingly, David HaMelech tells us that to “choose good” we must serve Hashem happily, and by serving Hashem happily we will perform what the Torah calls “good.”
As we approach Rosh HaShanah we must reflect not only on our actual performance of Mitzvot but also on our mindset while doing them. Even if we do the correct Mitzvot but lack the proper enthusiasm we will be lacking in the “good” that the Torah demands from us.