Mark Harmon in "NCIS." (Sonja Flemming/CBS/HO)

Maybe people just like Mark Harmon. Perhaps it’s as simple as that.

Harmon has been a staple on TV in various shows since the 1970s. But he hits a new milestone this week when his current series NCIS airs its 200th episode.

“We’re celebrating 200 episodes, but it doesn’t feel like 200, it doesn’t feel like nine years,” Harmon said. “This remains fresh. The 200th episode was as challenging as any episode we’ve done.”

The 200th episode of NCIS, titled Life Before His Eyes, airs Monday, Feb. 6 on Global, and then Tuesday, Feb. 7 on CBS.

During a routine stop at a local diner for his morning coffee, Gibbs (Harmon) comes face-to-face with the barrel of a gun. The incident forces Gibbs to question the choices he has made, past and present.

“There’s a work ethic in television that I understand,” said Harmon, asked to explain his boob-tube longevity. “I understand the team concept of it and the quickness of it and the fact that you can maybe, if you’re lucky enough and work hard enough, have what (NCIS) is right now.”