Where does your strength come from? Strength is mentioned over 360 times in the Bible, regarding both natural and supernatural strength. Believers have the unlimited power of Christ as the source of their strength. Jeremiah 9:23-24 "Thus says the Lord: “Let not the wise man boast in his wisdom, let not the mighty man boast in his might, let not the rich man boast in his riches, but let him who boasts boast in this, that he understands and knows me, that I am the Lord who practices steadfast love, justice, and righteousness in the earth. For in these things I delight, declares the Lord.”
"The Bible places an emphasis on God’s strength in our salvation. Man can in no way save himself. Only God can save. Paul makes this abundantly clear: “For it is by grace you have been saved, through faith—and this not from yourselves, it is the gift of God—not by works, so that no one can boast” (Ephesians 2:8–9). These two verses are the most forceful summary of the dynamics of salvation found anywhere in the Bible. They help us to understand the contrast between man’s total helplessness and God’s insuperable strength. “God alone . has the power to save or to destroy” (James 4:12, NLT)." [gotquestions.org]
Surrender is related to our amount of strength. Total submission to the Lord enables us to stand against the deceptions of Satan. We must align ourselves with the Lord thru submission to His will and works. James 4:7 says "Submit yourselves therefore to God. Resist the devil, and he will flee from you."
God's children are strengthened by:
His grace...Hebrews 13:9, "Do not be led away by diverse and strange teachings, for it is good for the heart to be strengthened by grace, not by foods, which have not benefited those devoted to them."
Our time spent in prayer...Ephesians 6:18, "And pray in the Spirit on all occasions with all kinds of prayers and requests. With this in mind, be alert and always keep on praying for all the Lord’s people."
The promise that God will reward our efforts....Galatians 6:9, "Let us not become weary in doing good, for at the proper time we will reap a harvest if we do not give up."
As for myself, my physical strength gradually vanished right before my own eyes. Out of my control, but always in God's allowance and control. God gives me strength to endure the long stretches of without, the perseverance to keep serving without an expectation of something in return, and the maintaining of peace in my heart that everything is working for my good. I pray for strength now in the battle that is Yours Lord. "I am strong because I've been weak, I am fearless because I've been afraid, and I am wise because I've been foolish."