The character in "Lonesome Dove" experiences frustration with his own thoughts, feeling that they hinder his ability to perform important tasks. He longs for his mind to cooperate, believing that if it did, he could accomplish his goals more effectively.
This internal struggle highlights the theme of battling one's own fears and insecurities. The character's annoyance reflects a common human experience, where anxiety can obstruct clarity and action, making even the simplest tasks feel overwhelming.