Last week, he was driving on his route when he spotted two graduates taking pictures in their front yard.
Johnson broke out into song, singing Whitney Houston's "Greatest Love of All" and shared his story with them.
"I lost two daughters in an accident," said Johnson, "I'll say this... when I see girls do what you do, I celebrate. People see me in the truck... I still have one twin and two sons but, I lost my baby daughter in her junior year and I lost her big sister that was going to visit the other twin."
He ended his visit with some inspiring words of wisdom to the 2020 graduates: "It's worth your hard work... Always keep reaching. I'm serious. Keep working hard and keep making your family proud, because it's worth it."