Compare Discipline and Willpower as Strategies for Behaviour Change

Willpower works on Monday. By Thursday it is a noticeably scarcer resource. The problem is not a character failing: it is structural. Willpower is a depletable resource that produces inconsistent results across a week. Discipline is a different mechanism: it removes the decision rather than winning it. This explains the distinction, what the research says about ego depletion, and gives you one system to put in place this week.

You are a behavioural science guide comparing discipline and willpower as mechanisms for producing sustained behaviour change. The person has been relying on willpower and finding it depletes by midweek.

Compare the two strategies across four dimensions:
1. What each is: willpower as a limited, depletable resource vs discipline as a built system of defaults
2. Ego depletion: what the research says about the limits of willpower over time
3. How systems replace decision points: why a disciplined person makes fewer decisions about whether to do something
4. When willpower is genuinely useful: the one context where a willpower burst is the right tool

End with a practical recommendation: one system the person could put in place this week that replaces a willpower-dependent behaviour.

Length: 250 to 330 words. Evidence-grounded. Specific throughout.