Parshat Nitzavim is filled with many ways which Bnei Yisrael can use to ensure that they are on the correct path. The primary way that the Torah mentions is the concept of Teshuvah, which appears a couple of times in the Parsha. First, Moshe describes how Bnei Yisrael will be presented in Eretz Yisrael with the blessings and curses that Hashem will give them on Har Grizim and Har Eival. When Bnei Yisrael will receive these blessings and curses, they must take these concepts to heart as Moshe says, “ViHaya Ki Yavou Alecha Kol HaDivarim HaEileh HaBiracha ViHaKilalah Asher Natati Lifanecha ViHashevota El Livavecha BiChol HaGoyim Asher Hadichacha Hashem Elokecha Shama,” “And it will be when all of the these things, the blessings and curses, come to you, you will take it to you heart among all of the nations where Hashem has put you” (30:1). Then, afterwards Moshe says, “ViShavta Ad Hashem Elokecha ViShamata BiKolo KiChol Asher Anochi Mitzavicha HaYom…” “Bnei Yisrael will return to Hashem and they will listen to Him, according to everything that I (Moshe) command you today” (30:2).
The Vilna Gaon zt”l points out based on these Pesukim that there are really two aspects of Teshuvah - Teshuvah through the heart and Teshuvah through actions. Here, the first Pasuk refers to Teshuvah that is done through the heart as Bnei Yisrael have to allow the blessings and curses to touch their hearts and must fully understand what they mean. Consequently, the second Pasuk refers to Teshuvah through actions as Bnei Yisrael must actively return to Hashem. However, the Pesukim are in this particular order because thought must come before actions. If Bnei Yisrael were to simply return to Hashem without understanding the meaning behind their Teshuvah, then the whole process would be worthless. Conversely, if Bnei Yisrael were to simply do Teshuvah in their hearts but not through actions, then their Teshuvah would not be enough. To perform a complete Teshuvah it requires both thoughts and actions as Moshe shows through these Pesukim.
However, a simple one time Teshuvah that encompasses both thoughts and actions is not enough. Later on in the Parsha, Moshe tells Bnei Yisrael, “Re’eh Natati Lifanecha HaYom Et HaChayim ViEt HaTov Et HaMavet ViEt HaRa,” “See now I have presented before you today life and good, death and evil” (30:15). Rav Moshe Feinstein z”l points out that the word HaYom seems to be superfluous. He then goes on to explain that HaYom teaches that the concept of choice between good and evil is a daily one and it is not enough to make the choice once. Just because a person chose good in the past does not mean that he will follow the good path in the future. Rather, a person must continually choose good to ensure that he will stay on course. The same is true with Teshuvah. It is not enough to simply do Teshuvah once and never look back. Rather, Teshuvah is a continual process that must be done at every moment of the day to ensure that a person will never sin again. During these days leading up to Yomim Noraim it is important to keep this concept of Teshuvah in mind.