AAAAALLRIGHT ASPIRING CONCEPT ARTISTS, ILLUSTRATORS, ANIMATORS, AND OR JUST ARTISTS IN GENERAL.
THIS IS A BEAUTIFUL EXERCISE I REALLY RECOMMEND YOU ALL DO.
In the red, we have a skeletal study—finding out where the bones or structure of the character would be. In blue we have the peices of the characters split into different shapes to make them easier to draw and remember. Green is mass shapes and masses. Purple is the line of action.
Guys, I have like. A bazillion times more understanding of the characters above than I had before. I completely recommend doing this: study their skeleton and then dominant shapes and masses. It will give you a better understanding of how your character moves and is held together.
The line of motion helps you make your character move in a more interesting fashion. It helps you see their movement and motion in a better light, and where there weight is being distributed.
And there you go.