What does it mean that every decision depletes willpower?

Decision fatigue is real — each choice you make reduces your capacity for subsequent choices.

Example: A product manager spends the first two hours of her day in a sprint planning meeting, making thirty-seven discrete prioritization decisions — which features to include, which bugs to defer, which trade-offs to accept. By the time the meeting ends and she opens her inbox, she faces a request from a partner team to change the integration timeline. It is the most consequential decision she will make all week, and she makes it in under two minutes, accepting the first option presented without negotiation. She does not feel tired. She does not notice the degradation. She simply lacks the deliberative capacity to engage the decision with the rigor it deserves, because thirty-seven smaller decisions have already drawn down the account. She will not realize what happened until the consequences arrive weeks later.

Try this: Run a three-day decision depletion audit. Each day, carry a small notebook or keep a running note on your phone. Every time you make a deliberate choice — not automatic habits, but decisions where you pause, weigh, or negotiate with yourself — mark a tally and note the time. At the end of each day, review the log and identify: (1) when your decision volume peaked, (2) when you made your most important decisions relative to that peak, and (3) any decisions you made on autopilot that deserved more deliberation. On day four, redesign one segment of your day so that your highest-stakes decisions occur before your highest-volume decision periods.