Don’t believe that “willpower is like a muscle that runs out after use”

Cost: No cost at all. All that needs changing is the way we talk about it.
In plain terms: The popular idea is that after doing something that requires self‑control, it becomes easier to give in to temptation later on, so we should “save” our willpower. Yet 23 laboratories and 2,141 participants repeated this experiment using the same protocol, and the results were essentially null. Stop using “I’ve run out of willpower today” as an excuse, and don’t spend money on courses that promise to help you conserve it.
Benefit: In a multi‑lab preregistered replication study, 23 labs with 2,141 participants followed Sripada et al.’s standardised procedure: first they performed a task demanding self‑control, then a second similar task. The pooled results showed a very small self‑exhaustion effect; its 95 % confidence interval included 0 (d = 0.04, 95 % CI −0.07 to 0.15). Another replication, also preregistered, involved 36 labs and 3,531 participants and yielded d = 0.06 — again a negligible effect. These findings call into question the model that self‑control is a limited resource.
Evidence grade: A
Sources:Hagger MS, Chatzisarantis NLD, Alberts H, et al. (2016). A Multilab Preregistered Replication of the Ego-Depletion Effect. Perspectives on Psychological Science, 11(4), 546–573. https://doi.org/10.1177/1745691616652873；Vohs et al. (2021). A Multisite Preregistered Paradigmatic Test of the Ego-Depletion Effect. Psychological Science. https://doi.org/10.1177/0956797621989733
Notes: What’s being refuted is the notion that self‑control is a consumable resource, not that people can become fatigued. Lack of sleep or prolonged effort does reduce performance, but that falls under the guidelines on sleep and working hours in Section 3. The only evidence‑based actions are environmental tweaks and simple wording changes, as described in Section 4, items 10 (“move unwanted items out of reach”) and 1 (“write down exactly when, where and what you’ll do”). Fixing routine choices such as clothing and diet is still worthwhile because it costs almost nothing. It saves minutes and mental effort, not “willpower”; don’t expect it to improve your judgment later in the day. While other items in this section deal with monetary costs, this one concerns time and mental energy, which aren’t interchangeable.