To prepare for her role as Captain Marvel, Brie Larson underwent extensive physical training. But one part of training she didn’t expect? Perfecting her “cool face.” The actress appeared on Jimmy Kimmel Live! on Monday, March 4th, revealing that she found this to be one of the least intuitive parts of the whole process.

She said her stunt team helped her out, telling her to bend her knees and clench her fists and jaw. She also had to turn around super slowly without smiling, which was actually the hardest part for her.

The Oscar-winner then showed off her Captain Marvel “cool face”—and it’s even cooler than we expected.

Check out Larson’s whole interview below:

Captain Marvel hits theaters this Friday, March 8th, and we can’t freaking wait.