By Meredith Lepore
Mar 18, 2016 @ 8:30 am

For years Jennifer Garner stayed in tip-top shape for her role as undercover agent Sydney Bristow on the hit show Alias. But based on what she told Seth Meyers on Late Night Thursday, the physical demands for the role did not compare to her training for the John Adams junior high marching band.

"You were so kick-ass on that show, but yet from your early career it maybe would not have been easy to predict how kick-ass you would be in Alias," Meyers noted. "So you were full marching band?"

"Absolutely," Garner replied assertively. Meyers showed two pictures of a young, slightly dorkier, Garner in her band gear holding Sally the Sexy Saxophone, which she explained was her name for the instrument. "This is parade formation," she pointed out in the photo. "Clearly I'm breaking it to wave to my mom or something."

The Miracles from Heaven actress then delved into the difficulties of marching in a band: You have to walk very smoothly so you don't jostle around your instrument, but you have to be very alert at the same time while following the person in front of you. "You cannot mess around!" she said. "You go to band camp, you stand in the sun, and you practice marching at the same steady level of gait. It's not easy, Seth!"

Meyers asked about the whereabouts of Sally the Sexy Saxophone now. "Well, I lost her," said Garner. "I don't know where she is."

"Obviously you cared about her very deeply," Meyers joked. "You know where your kids are, yes? All three?"

"In theory," Garner replied with a smile.

Watch Garner talk about her marching band days in the video above.