In John Scalzi's "Old Man's War," the theme of battles is explored through the perspective of individuals who must confront challenges beyond their control. The quote "We don't get to choose our battles" reflects the notion that life's conflicts often emerge unexpectedly, forcing people to respond and adapt to circumstances they did not select. This highlights the unpredictable nature of existence and the resilience required to navigate through adversities.

The characters in the book exemplify this struggle, as they engage in conflicts that test their limits and moral compass. Scalzi illustrates that while one may not have the freedom to select their battles, the way they respond defines their character and ultimately shapes their journey. This resonates with many readers, as it captures the essence of humanity’s experience in facing obstacles with courage and determination.