What does it mean that commitment scope matters?

Commit to small specific actions rather than large vague goals.

Example: You tell yourself 'I'm going to get in shape this year.' Six weeks later, nothing has changed. The commitment was real — you meant it. But it gave your doer self nothing to execute. There was no when, no where, no how much, no definition of done. Now compare: 'I will walk for 20 minutes after lunch on Monday, Wednesday, and Friday, starting from the back door of my office.' That commitment has a trigger (after lunch), a behavior (walk), a duration (20 minutes), a frequency (three days), a location (back door), and a start condition (this week). Your planner self has handed your doer self an instruction set instead of an aspiration. One of these survives contact with a busy Tuesday. The other doesn't.

Try this: Take your single most important active commitment — the one you most want to follow through on. Write it down exactly as it currently lives in your head. Now score it on the five dimensions of scope: Does it specify when? Where? How much? How long? What counts as done? For every missing dimension, add it. Rewrite the commitment as a scoped action statement with all five dimensions present. The rewritten version should be something a stranger could verify without asking you any clarifying questions. If it isn't, it's still too vague.