Peace. We often know it most by its absence. We can go for weeks or months resting well at night and easily take peace for granted. We don't think "Wow, I feel really peaceful today". We recognize immediately, though, when it is absent.
An unexpected medical diagnosis. A middle-of-the-night phone call. A child who doesn't come home one night. All things that throw us into immediate anxiety. In crisis mode, peace is naturally elusive.
As much as we might wish otherwise, Jesus didn't come to erase all challenges to our peace. God never promises the absence of struggles. Instead, He gives us something much greater: a Son - one who will be called "Prince of Peace".
The Son, of course, is Jesus. Jesus came first of all to bring us to peace with God. Romans 5 says that we were God's enemies, but He sent Jesus to demonstrate His love for us so that we could enter His peace. Secondly, Jesus came to be peace between people. Ephesians 2:14 says "For He Himself is our peace, who made both groups [Jews and Gentiles] into one and broke down the barrier of the dividing wall ...". The presence of Jesus, the Prince of Peace, brings peace to individuals and to people groups. When we unite around Jesus, we find that He brings peace into situations we thought were hopeless.
Then when we do face those inevitable struggles of life, we have the guarantee of His presence. Like Peter, who slept while imprisoned, or Paul and Silas, who led a worship service at midnight from jail, we can find peace despite our circumstances. Not because of the absence of challenges, but because of the presence of a Person.