it's not about our strength. it is about the Holy Spirit in us strengthening us
but you will receive power when the Holy Spirit has come upon you; and you shall be My witnesses both in Jerusalem, and in all Judea and Samaria, and even to the remotest part of the earth.” Acts 1:8
that He would grant you, according to the riches of His glory, to be strengthened with power through His Spirit in the inner man,
Ephesians 3:16
Finally, be strong in the Lord and in the strength of His might. Ephesians 6:10
Now may our Lord Jesus Christ Himself and God our Father, who has loved us and given us eternal comfort and good hope by grace, comfort and strengthen your hearts in every good work and word.
2 Thessalonians 2:16-17
I thank Christ Jesus our Lord, who has strengthened me, because He considered me faithful, putting me into service, 1 Timothy 1:12
and there are many many more, including in the OT