i'm confused tho, its quite a jump from the ribs to the scm right?

i recently foudn out i have a pigeon chest

i would think it's okay to use the ribs, my pt makes a big deal about the motion being smooth like a wave

my scm is a mess though, that's why im chin tucking. stretching is aggravating.

she gave me a bunch of new exercises, one is for spine mobilization. you kind of roll the spine from lying down to sitting up, one vertebrae at a time. im very bad at it