Gisele B ndchen planks with Jimmy Fallon
Credit: Douglas Gorenstein/NBC

When Jimmy Fallon isn't rolling around on the floor with supermodels, he's learning how to do planking exercises with them. (Tough gig, right?) On Thursday, Gisele Bündchen stopped by The Tonight Show and, after Fallon marveled at her yoga photos on Instagram, she offered to teach him how to get into position. "We're gonna practice that, you and I," the new Under Armour spokeswoman promised the host.

After getting encouragement from the crowd, Fallon agreed to let Bündchen—who was wary of having a wardrobe malfunction in her chic black corset top during the segment ("I'm a mother!")—be his yoga instructor. While most of us would have a hard time keeping up with the toned beauty, Fallon seemed to have a really hard time ... just trying not to stare. "My wife is gonna kill me," he joked.

Though she did her best to teach him the exercise and the core-strengthening benefits, the results were more hilarious than they were beneficial. Watch Bündchen's fitness session with Fallon below: