Paul had every reason to be afraid. He has spent the day before the Jewish high court. Paul's bold testimony about the risen Jesus has filled the members of the court with hatred and rage. It was this group that orchestrated the death of Jesus. They have the power to do the same to Paul. His life hangs in the balance.
While chained and under guard in the barracks, the Lord suddenly appeared to Paul. The apostle hears the words that the Lord utters to those who are afraid - "Take Courage!" Paul received reassurance that his mission is not going to end in Jerusalem. The Lord has another place where Paul will proclaim the good news of the suffering, death and resurrection of Jesus - Rome, the seat of the world's power in that day.
The Lord's comforting words to Paul reminds of another time when the disciples were filled with fear. Read Mark 6:45-52 when you have a moment. The disciples were out in the lake, caught in the middle of a violent storm. It was all they could do to keep the boat afloat. Exhausted from the struggles, the disciples were filled with fear as they saw what the though was a ghost walking on the water. Instead, it was the Lord they saw. Jesus called out to them, "Take Courage! It is I. Don't be afraid." As the Lord climbed into the boat, the winds died down. The disciples relaxed. The Lord was with them.
The Lord is with you each day. He is present always until the end of the age. The next time you are afraid, remember the words God said to Joshua: Be strong and courageous. Do not be terrified; do not be discouraged, for the Lord your God will be with you wherever you go."