A Variety of Pressure Creates Emphasis. If there are some areas you want to accent, you can press a little harder on the crayon and end up with a darker, more intense color. This is another good reason to color lightly for full coverage. For example, in this picture of the heart below, I pressed harder when tracing the lines within the heart and in the vein and artery openings. I did the same thing when coloring the muscles and the brain.
In fact, taking a crayon or colored pencil to paper is a therapy method that dates back to the early 20th century _ though it seems people are just starting to rediscover its benefits. So how exactly does something as simple and seemingly childlike as filling in the lines lend itself to combating adult amounts of stress?