Breathe like a baby, people say. See how their little bellies move? Well, actually, their bellies are moving so much because they are working HARD for each breath. This is why belly breathing - and breathing like a baby when you are a grownup - aren't always best.
Wondering why there's a picture of a jellyfish for a post about our diaphragms? Well, it's because your diaphragm, tucked up inside the base of your ribcage, is shaped like Darth Vader’s helmet or like a jellyfish. Its primary action is to lift and open your ribs, making space for breath to happen and it does that by moving much like a jellyfish does.