The format is small. “When I get into bed, I will plug my phone into the kitchen charger.” “If it is 10 PM on a weeknight, I will close the laptop.” The specificity is the point — vague intentions (“I want to use my phone less”) are routinely overridden by competing demands; if-then plans transfer control from conscious intent to environmental cue.
Effect sizes from meta-analyses are typically around d ≈ 0.5–0.7, which is large for behavior-change research. The effect depends on the cue being noticed when it occurs, so cue-rich plans (specific time, specific place) outperform cue-poor ones.
In practice
Daybreak encourages implementation-intention formats throughout. Focus rules are if-then by design. Recovery plans are templated as if-then chains. Dawn often guides users to commit to one specific if-then plan for the next week.
Source
See the Implementation Intentions summary for the underlying research (Gollwitzer, 1999).