At tennis on Saturday and soccer on Sunday, I put some of my attention toward watching my reactions to my performance, and I noticed that I am awfully hard on myself when I screw up, to the point that I usually err well on the side of staying safely in my comfort zone rather than even risk making a mistake.
Pushing against the limits of your abilities--and, yes, sometimes screwing up--is the path to improvement. Consequently, my pattern of harsh judgment toward myself keeps me from growing. And it's not like it even helps that much. I screw up plenty anyway.