In the last start of Johnson's high school career, he tossed a perfect game, which provided a portent of things to come for the Livermore High School graduate.
When asked to recall his high school perfecto, Johnson was reminded of how much he's accomplished since then.
"I don't even remember high school anymore," he joked. "The perfect game I threw last year in the Major Leagues is fresher than the one I threw in 1982. It was one of those games where everything came together. Everyone was playing well behind me. It was a game where everything was on."
Johnson blanked his high school opponents at a time when thoughts of playing baseball for a living were becoming more prominent for the lefty.
"During my senior year in high school, I realized that there were professional teams interested in me because there were scouts at my games," Johnson explained. "I realized that I had the potential to possibly make it to the Major Leagues because there were teams interested in my abilities.
"It took a little while after I was drafted by a Major League team to make it to the Majors, but the first step is when someone is interested in your ability," he continued. "That happened for me in high school."
With widespread interest from professional scouts, along with an athletic scholarship to the University of Southern California in hand, Johnson was faced with a crucial decision.
Despite being drafted by the Atlanta Braves in the third round of the 1982 amateur draft, the Big Unit chose to attend college.
"I just wanted to learn more and get a better education after high school," Johnson said. "Also, it was an opportunity to learn more about pitching. At such an early age, I thought I might get lost in the shuffle if I had gone directly into professional baseball. I didn't feel I was ready at that time to advance forward through the Minor Leagues."
In addition to his pitching prowess, Johnson starred on the hardwood. He decided to concentrate solely on baseball after competing in both sports during his first two years at USC.
"I played basketball along with baseball," he said. "I enjoyed both sports. I tried to get better every day in what I did. Eventually, I had to make a decision as to whether I wanted to pursue professional basketball or baseball, and I chose baseball."
Despite the rigors of playing two sports, Johnson never lost sight of his priorities and always understood the importance of education.
"It starts in the classroom," Johnson said. "You have to show a willingness to learn. It carries over into your athletic life when you see other athletes strive to do well in school and in sports.
"I didn't have a favorite subject," he continued. "I wanted to learn a little about everything. Not being great at one thing but being good at a lot of things is important in life."
In his youthful days, Johnson clearly had a lot going for him, yet something was missing.
Then came a seemingly insignificant exchange with a teammate.
"I was given [my nickname] when I first got called up to the big leagues in 1988 by a former teammate of mine, Tim Raines," the 6-foot-10 hurler recalled. "He was about 5-foot-9. He bumped into me, looked up and said, 'You're a big unit.'"
From that point on, Johnson never looked back, striking out more than 4,200 big league batters and racking up 250 wins, while also taking home five Cy Young Awards.