Similarly, we find this concept in Alshich Hakadosh, where he draws upon the last words of Dovid Hamelech to his son Shlomo. In his parting message, Dovid Hamelech gave a line of instructions to his son Shlomo. וַיִּקְרְבוּ יְמֵי־דָוִד לָמוּת וַיְצִו אֶת־שׁ־לֹמֹה בְנוֹ לֵאמֹר אָנֹכִי הֹלֵךְ בְּדֶרֶךְ כָּל־הָאָרֶשׂ וְהָזַקְתָּ וְהָיִיתָ לְאִישׁ And Dovid's days were nearing the time when he would die, and he commanded his son, Shlomo, saying: "I am going in the way of all the (inhabitants of) earth; be strong and be a man" (מלכים א' ב א-ב).
The Alshich Hakadosh says that these words should be understood as an instruction, rather than an introduction to his parting words. Dovid commanded his son to constantly say to himself: "I am soon going the way all the inhabitants of the earth do".
With this, Dovid Hamelech wanted his son to regularly remind himself that our days on earth are numbered. Therefore he should always envision himself as though he will have no more days to live. By referring to this day as his last day, he will "be strong and show himself as a man", that is, serve Hashem with utmost perfection. When living with such a mindset, he will surely strive to serve his Creator to the best of his abilities.