I started to see things very differently the more I drew.
Take this Irish dancer at a local féis for example. My eyes were working much harder than my pencil was. They were taking in the details that made each dancer unique, such as the way the gathered hair drooped at the back of the neck, the position of the chin, the relationship between the nose and the forehead.
When you train yourself to capture the essence of something in a drawing, you are training your brain and your eyes far more than your ability to make the physical marks with the pencil.