Acts 5:17-20 More than a few parents have been "guilty" of following their young children as they walk the short way to school. Their parental priority was protection -- but doing so invisibly, from a distance, so as to allow their child a sense of independence. As parents protect their children, so angels are sent to protect God's children.
In the angelic realm, protection as a responsibility is apparently well known. When Satan tempted Jesus, challenging Him to jump from the highest point of the temple, he quoted Psalm 91:11: "For He shall give His angels charge over you, to keep you in all your ways" (Matthew 4:6). In spite of that promise, Jesus didn't yield to the devil's challenge. And neither should we act foolishly, expecting to be protected by angels. But we can be assured that angels -- our unseen guardians -- are aware of our steps and are there to protect and minister to us.
Every moment of the day -- especially when traveling or heading into challenging situations -- is a good time to thank God for the angels who are there to care for you.
Mercifully grant that, as your holy angels always serve and worship you in heaven, so by your appointment they may help and defend us here on earth.
Book of Common Prayer