The "NCIS" franchise is still going strong after 1,000 episodes across more than 20 years, and is gearing up for yet another spinoff this fall on the 2024 TV schedule. For a first in the franchise, there will be a prequel series centered on Mark Harmon’s beloved character, Leroy Jethro Gibbs. Harmon is serving as executive producer and narrator on 'NCIS: Origins,' but when it came to casting his character's younger self, the actor only had two words to say to actor Austin Stowell.

Playing an already-established and loved character is not easy, and Stowell has some big shoes to fill taking over for Harmon. With the series taking place in 1991, fans will be seeing a new side of Gibbs. While it may seem a bit overwhelming, during a Television Critics Association panel, Stowell shared the wise advice Harmon gave him. It may be short, but it’s definitely the most important one to remember