Inside Mark Harmon's Awkward First Foray Into Acting

Mark Harmon was already an acting veteran before he was cast as special agent Jethro Leroy Gibbs in "NCIS." But fans might be a little surprised just how far back they'd have to look to find Mark's first acting role.

A very young Mark appeared in a television commercial alongside his late father Tom Harmon in the 1970s. Like Mark, Tom was also a fairly famous and familiar face back in his time. The elder Harmon gained his celebrity by playing football for the Los Angeles Rams for a couple of seasons. Afterward, his voice might've become more popular than his face when he pursued a career as a sports broadcaster.

According to Mark, his father had another lucrative side hustle as a spokesman for Kellogg's cereal. While doing the gig, one of his duties was appearing in commercials to help advertise Kellogg's many brands. When Tom was hired to star in an ad for the cereal Product 19, the former athlete asked his son to appear with him. "I was in a commercial in the backyard eating cereal, which, that never happened," Mark said in an interview on "Live with Kelly and Mark."

Looking back on his first unofficial acting role, Mark admitted to being pretty embarrassed by the commercial. If there's anything positive he gained from the experience, however, it was getting his first taste of the acting industry. "I think I saw something, that crew, those people around, that I understood," Mark said.

Despite, or perhaps even because of his humiliating Kellogg's commercial, Mark Harmon didn't consider acting full-time until his adult years. For a while, it seemed Mark might follow in his father Tom Harmon's footsteps. Mark was an avid football player, having played for the Bruins at UCLA in his young adult years. But surprisingly, if he didn't become an actor, Mark said he might've gone into carpentry instead. It was yet another skill he might've inherited from his father, who was also a bit of a handyman. "I tried to do that, but I just couldn't get hired. I enjoyed getting up and doing that in the morning; I enjoyed the drive to work. For me it was about materials and doing right," Mark said in an interview with Men's Journal.

But not being hired as a carpenter was the best thing to happen to Mark, as it paved the way for his highly lucrative acting career and his run on "NCIS." Even after all these years, however, Mark hasn't left his passion for craftsmanship behind. Nowadays, it seems it's become more of a hobby for the "Freaky Friday" star. "I still enjoy [carpentry]," he said.