Earlier in this chapter, Jeremiah poured out his complaints to the Lord while in the stocks. He had faithfully proclaimed God's word and had received nothing in return but persecution and sorrow. Fortunately, faith came to Jeremiah's rescue and began to strengthen him. 
Here is what the prophet does. He starts with God. Because the Lord is with us [that is the first thing to remember], and he is a mighty warrior [he knows how to fight and how to defend against attacks], our persecutors will stumble [their plans will fail], and they will not prevail over us. In fact, they will be greatly ashamed, for they will not succeed, and God will never forget their disgrace. Jeremiah, assured by faith, thinks this will occur. The same is true for us.
The Lord is with me and you - He is our ally - yet to the devil and the powers of darkness, He is the Mighty Terrible One to be feared! We will win against all odds because our Lord is with us!

Dear Heavenly Father, You are the mighty warrior I desperately need right now. Lord, surround me with Your love, Your peace, and Your mighty power. I know You are always with me and will help me in overcoming the obstacles in my life. Give me the strength to remain faithful despite the circumstances. Thank You, Father, for Your everlasting love, and thanks to You, Jesus, I am undefeatable. 
In Jesus's name I pray. Amen.