Lobsters have body language, and this affects their brain chemsitry and their chances of survival. Why is this important to us? Well from an evolutionary perspective Lobsters predate us and the dinosaurs by a couple of million years so body language is hard wired into our DNA.
Closer to home research by Amy Cuddy has shown that adopting a high power posture for 2 minutes has shown to increase testosterone and decrease cortisol. I.e. you feel better for it.
In workouts, our body language matters. Approaching a metcon or a lift with a confident body posture is better than slumping up to it. And it’s always why we don’t lie down after workouts. That’s telling our brain we were defeated and beaten by the workout. A much better approach is the Mat Fraser “crouch and fist pump” or the Josh Bridges “Whoooooo!” (which he probably got from Ric Flair)