Peace is a gift from God. Jesus had made peace with God on our behalf when He paid the price of our sins on the cross. Unlike worldly peace, which is circumstantial and usually defined as the absence of conflict, Jesus's peace is eternal and gives us perfect stillness in our heart, mind, and soul that "transcends all understanding" (Philippians 4:7). 
We experience fear and worry on a daily basis. We tend to worry more than we ought to pray, and we frequently forget to seek God's peace but rather rely on our human understanding to try to make sense of things. It is clear from Jesus' words that nothing in this world can truly give us the peace that our souls long for. We were created by God, so our peace can only be found in Him. Jesus has made that perfect peace available to all of us. All we need to do is accept and believe it.
When life becomes stressful, be still in the Lord's presence and allow Him to fill you with His perfect peace. Do not let your heart be troubled or afraid because God is in control, and He will carry you through whatever life throws at you.

Dear Heavenly Father, thank You for Your love and mercy. Please shower Your peace on me right now and help me to rest in Your perfect peace. I give You all of my worries and trust that You will see me through the challenges that I face. Life is difficult, but I know I can overcome anything with You walking by my side. Lord, please replace the fear and worry in my heart with courage and strength. 
In Jesus's name I pray. Amen.