Mark Harmon made his television debut in a Kellogg’s commercial with his father

Mark Harmon was initially not too happy about his acting debut.

The actor, 73, recently joined Kelly Ripa and Mark Consuelos for Lives with Kelly and Mark in Palm Springs on Wednesday, November 13. During their conversation, he told daytime talk show hosts that his first role was actually alongside his father, football and television icon Tom Harmon.

The NCIS star explained that his father was a Kellogg’s spokesperson and he was asked to join him in a commercial for one of its products, specifically Product 19 cereal.

“I was in a commercial in the backyard eating cereal, which never happened,” he joked with Ripa, 54, and Consuelos, 53. Harmon confirmed that he had just started high school at the time.

“So I imagine my own kids. Would that be embarrassing for you—” Ripa began, before the Emmy nominee immediately interjected, confirming that it was “humiliating.”

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While people didn’t start recognizing him, the commercial changed (his) direction a little bit, Harmon said. “I think I saw something, that crew, those people around, that I understood.”

Consuelos chimed in and said, “Also, the paycheck is nice. Did you get paid for that ad?”

“My dad did. I think,” Harmon said, laughing. “I think they have laws against it now,” Consuelos added, and Harmon replied, “Not back then!”

Since the first commercial, Harmon has starred in several projects, from Cool Friday to Moonlight and St. Elsewherebut he held his ground NCIS character, Special Agent Leroy Jethro Gibbs, for nearly two decades.

Harmon starred in the military police procedural for 19 seasons until his departure in 2021. Since its premiere in 2003, the series has spawned five spinoffs: NCIS: Los Angeles, NCIS: Hawaiʻi, NCIS: New Orleans, NCIS: Sydney and NCIS: Origins.

In a 2019 interview with PEOPLE, Harmon revealed the secret to his success, which he attributes to his late father’s advice.

“My father taught me that if it’s not true, don’t worry about it,” the NCIS star said of her father, who died in 1990 at the age of 70. “I come from labor and I’m proud of that. You have to get up every day and just try hard”

At the time, Harmon explained that even though his father had passed nearly three decades before, he continued to implement his father’s advice.

“Strip off and don’t let the effort show,” he said. “Also: Treat people equally, not based on who they are or what they are. Show them common kindness. Don’t be colored by their fame or profession. I don’t really get turned on by people blowing smoke at me. You have to stay honest.”

Harmon serves as narrator and executive producer on NCIS: Originswhich is broadcast on CBS on Mondays at 10 p.m. ET.