Another interpretation: "My strength" means none other than might, as it is said, "O LORD, my strength and my stronghold, my refuge in the day of trouble" (Jeremiah 16:19), and it says, "my strength and my shield; in Him my heart trusted" (Psalms 28:7).
My Strength Is My Stronghold in the Day of Trouble
Yalkut Shimoni on Torah 244:3
דָּבָר אַחֵר, אֵין עָזִּי אֶלָּא תֹּקֶף, שֶׁנֶּאֱמַר (ירמיה טז, יט) "ה' עֻזִּי וּמָעֻזִּי וּמְנוּסִי בְּיוֹם צָרָה", וְאוֹמֵר "עֻזִּי וּמָגִנִּי בּוֹ בָטַח לִבִּי" וְגוֹ'.