Challenge: Mindful Doodles
Jackie Andrade who has studied doodling has reported that research has shown that people who doodle while listening to a monotonous phone call were able to recall 29% more information after the call. 
A 1938 study analyzed 9000 different doodles had found that spontaneous drawing was able to calm the mind by quieting the mental thoughts of the left hemisphere of the brain while increasing the right hemisphere. This part of the brain is used for creative thoughts and activities. 
1. Maclay WS, Guttman E, Mayer-Gross W. Spontaneous Drawings as an Approach to some Problems of Psychopathology. Proceedings of the Royal Society of Medicine. 1938;31(11):1337–1350.
2. Andrade J. What does doodling do?. Applied Cognitive Psychology. 2010;24(1):100–106.