What will surely go down as one the most stressful movies of the year is “If I Had Legs I’d Kick You,” which premiered Friday at the Sundance Film Festival.

Sundance: After Mary Bronstein's exhilarating, big-screen anxiety attack premiered, co-star Conan O'Brien said he's surprised the amazing Byrne wasn't hospitalized after filming.

From left, Conan O'Brien, Mary Bronstein and Rose Byrne attend the premiere of "If I Had Legs I'd Kick You" during the Sundance Film Festival on Friday at Library Theatre

Rose Byrne is incredible in Mary Bornstein's 'If I Had Legs I'd Kick You,' A24's anxiety-fueled thriller on a mother with no more f's to give

Contrary to its title, everyone in If I Had Legs I’d Kick You has their appendages. Rose Byrne’s protagonist, however, does have a wealth of problems and neuroses, and writer/director Mary Bronstein dives into her headspace with a full-bore intensity and immediacy that’s bracing at first,

Creator Mary Bronstein and star Rose Byrne stop by THR's studio in Park City to dish all about their film If 'I Had Legs I'd Kick You.' They break down the meaning behind the movie, the difficulties of motherhood and more.