You see the model’s back leg pushing off, the front leg sliding, and the torso twisted. Draw a 2-inch thumbnail to capture that "C-curve" energy.

Every artist knows the struggle. You have a vision of a warrior woman leaping through the air, a spy crouching in the shadows, or a gymnast executing a perfect twist. But when the pencil hits the paper, the figure looks stiff, unbalanced, or simply... boring.

Now zoom in on the PDF. Look at the Latissimus dorsi (back muscles). See how they stretch over the ribs on the reaching side? See how they bunch up on the pulling side? Add those shadows.