NBC host Jimmy Fallon took a slightly different tack on President's Day, engaging in a fitness challenge with First Lady Michelle Obama for a good cause -- mostly.

"The most important thing for the kids to learn is that it's all about being active and having fun," Fallon told Obama, who developed the Let's Move initiative to get kids more involved in fitness. "It doesn't matter if you won or if you lost, you know?"

"It matters," she replied, drolly.

The First Lady, Fallon quickly learned, was playing for keeps in their best-of-five competition, from admonishing him over picking an all-blue unitard ("No way, Jimmy") to enlisting the help of security guard "Harry" to get the edge in a game of tug-of-war.

It turned out to be in vain, as Fallon bested her in that event and a hula hoop-off, while Obama bested him at dodgeball and did more push-ups, setting the stage for a potato-sack race for bragging rights (set to the title song from "Chariots of Fire," of course). Unfortunately for Fallon, he came up just short at the finish line.

Watch the First Lady and the Late Night host square off, as aired on NBC Monday, below.