Drawing on the Right Side of the Brain: The Definitive, 4th Edition recommended to do blind contour to train your brain to really see what is in front of you, and not to worry about what your drawings really turned out to be. Once you get the hand of it, it was quite a special experience. Before each drawing section, starting with blind contour will be like the medication for the brain. It could calm your busy mind down and make you concentrate better for the following drawing section.
A few of my blind contours.