What goes wrong when you ignore that the routine is the behavior itself?

The most common reason fails: Defining the routine as an outcome rather than a process. "Meditate until I feel calm" is an outcome routine — it depends on an internal state you cannot control, which means you can never be certain whether you completed the habit. "Sit on the cushion, close my eyes, and follow my breath for five minutes" is a process routine — it is entirely within your control and unambiguous in its completion criteria.

The fix: Choose one habit you are currently trying to build. Write down the routine as you currently conceive of it. Now apply the script test: could a stranger read your description and execute the behavior with zero interpretation? If not, rewrite the routine until every physical action is specified — what you open, where you sit, how long you do it, and what signals completion. Read the rewritten version aloud. If it sounds like stage directions, you have it right.

The underlying principle is straightforward: The routine should be clearly defined so there is no ambiguity about what to do.