רַק֩ חֲזַ֨ק וֶֽאֱמַ֜ץ מְאֹ֗ד לִשְׁמֹ֤ר לַעֲשׂוֹת֙ כְּכָל־הַתּוֹרָ֗ה אֲשֶׁ֤ר צִוְּךָ֙ מֹשֶׁ֣ה עַבְדִּ֔י אַל־תָּס֥וּר מִמֶּ֖נּוּ יָמִ֣ין וּשְׂמֹ֑אול לְמַ֣עַן תַּשְׂכִּ֔יל בְּכֹ֖ל אֲשֶׁ֥ר תֵּלֵֽךְ׃
오직 너는 마음을 강하게 하고 극히 담대히 하여 나의 종 모세가 네게 명한 율법을 다 지켜 행하고 좌로나 우로나 치우치지 말라 그리하면 어디로 가든지 형통하리니
Mesillat Yesharim
If he leaves himself in the hands of his [natural] heaviness, it is a certainty that he will not succeed. This is what the Tana (Mishnaic sage) stated: "be brazen as a leopard, light as an eagle, swift as a deer, and mighty as a lion to do the will of your Father in Heaven" (Avot 5:20). Likewise, the Sages counted among the things which need strengthening: "Torah and good deeds" (Berachot 32b). This is explicitly stated in scripture: "be strong and very courageous [to observe and do all of the Torah...]" (Yehoshua 1:6). For great strengthening is needed for one who wants to bend his nature to its opposite.
Mesillat Yesharim
Before beginning a deed: that one not allow a Mitzva to become delayed (lit. Chametz).