According to Grover, everyone is “born relentless” but is “taught to relent” (68). Babies and toddlers are governed by instinct and get their way through making demands. Over time, their behavior changes as they begin to listen to others’ opinions. He urges the reader to tap into their untamed brain or the “dark side” of their instincts—the side that “refuses to conform and behave” (69).

He compares the average person to a caged lion, arguing that if they free themselves from their cage, they can unleash their killer instinct. Grover believes that this “cage” is comprised of worry, over-analysis, and timid rule-following. While these traits can foster moderate success, Grover argues that the best of the best break out of these patterns. He claims that everyone would succeed more easily if they simply stopped thinking and trusted their instincts, lamenting that many problems in professional athletics arise from over-analysis, which leads to nerves and self-consciousness. Michael Jordan accomplished this instinctual state by not looking at the coaches’ play sheet or listening to their last-minute explanations; instead, he stayed in his zone and acted on impulse.

The author clarifies that instinct and talent must be honed through practice and hard work; his warning is not to ruin this process with overthinking. While “Closers” will use their head to find their goals and think about how to accomplish them, Cleaners already know what they want and have the confidence to apply themselves to get it. Grover recalls how, while studying kinesiology in college, people doubted his dream of training pro athletes. However, he trusted his gut and never let others’ doubts get to him. Looking back, he believes that this level of confidence in one’s own goals is an essential part of reaching them.

Grover’s broad claims mirror those made in other personal development books; for instance, Relentless’s emphasis on hard work over innate talent anticipated Angela Duckworth’s 2016 Grit. What distinguishes Grover’s approach is how far he pushes the idea, prioritizing drive over virtually everything else. For instance, his dismissal of rule-following as a barrier to success reflects the hypercompetitive landscape of professional athletics but may backfire in environments that are strongly hierarchical and/or communal.

Chapter Lessons

• Trust your instincts instead of overthinking.
• Find your inner fire and killer instinct and use them.
• Consider how you have been pressured to relent and undo these influences.

Reflection Questions

• Do you feel that everyone, regardless of personality, has a “killer instinct” within? Do you?
• How do you distinguish between your instincts and your thoughts? Which one do you listen to more?
• Which of your ambitions do you feel the most and least confident about? Why?