Tim Grover opens Relentless by introducing his central taxonomy of competitive performers: Coolers, Closers, and Cleaners — with Cleaners representing the rarest and most intensely driven category, the elite competitors Grover has trained across decades working with legendary professional athletes.

Grover's core distinctions:

• Coolers need external motivation and structure to perform; they're capable but require others to push them
• Closers can perform under pressure when the stakes are clear, but often need the moment to be defined for them
• Cleaners create their own intensity and standards regardless of external circumstances, and are often uncomfortable to be around because of the totality of their competitive commitment

Grover is explicit from the outset that this book isn't designed for readers seeking comfortable, balanced self-improvement — it's aimed specifically at readers pursuing truly elite-level competitive achievement, where the intensity described may be genuinely uncomfortable or even alienating to those not pursuing that level of pursuit.