Paul introduces the overall motivation for his instructions in this verse. Specifically, the secret of Christians’ victory is never in our own efforts but entirely in our trust in the Lord. Only by His mighty power can we be strong. 
We have access to tremendous heavenly blessings through Christ Jesus. In spite of this, every true believer soon realizes that we live in a world in which we are engaged in a war within the spiritual realm. It requires a supernatural power that is beyond our human limitations, which comes from the Lord. In our own strength, we cannot stand up to the evil plots and cruel strategies of the enemy. The Lord, however, is able to strengthen us through the power of His might.
Our strength comes only when we are aware of our weaknesses, inabilities, and ineffectiveness. In fact, God has chosen the foolish things of this world to confound the wise, and God has chosen the weak things of this world to confound the strong. It is only when we recognize our weaknesses and die to ourselves that we will be strong in the Lord and in the power of His might.

Dear Heavenly Father, thank You for providing me with all I need to be victorious in the spiritual battle in which all Your children are involved. It is now time for me to put on Your armor so that I will be able to defend myself against all that the devil will throw at me. Please help me to recognize my own weaknesses, inabilities, and lack of effectiveness. Let me place my trust in You rather than in my own abilities. Let the power of Your might enable me to find all I need in You. 
In Jesus's name I pray. Amen.