In 3-4 year old kids are more confident in coloring. They're not trying to draw freely, and act within the circuit, trying to repeat the figure bends.
In the process of painting you focus your attention on a subject that is at your fingertips. If you do it with enough concentration, it will ignore the extraneous noise, unpleasant thoughts and worries. This is a very useful skill that will be useful in situations where you need to briefly forget about your physical or emotional pain.