Distinguish repeating an action in a stable context from accumulating a streak.
Limited evidenceSupporting studies exist, but they are few and conditions matter.
Example
Editorial example: check one plan after a morning coffee.
Why it works
Lally and colleagues track self-reported automaticity while participants repeat chosen everyday behaviors. The rate varies between people; no universal duration follows.
On the web
Attach a small action to an existing routine and allow resumption after breaks. Track burden separately from streak length.
When it backfires
This observational study does not prove that notifications create habits. Do not promise completion in 66 days or any fixed duration.
Sources
Tracks self-reported automaticity during repetition and finds variation in formation rates.
Lally, P., van Jaarsveld, C. H. M., Potts, H. W. W., & Wardle, J. (2010). How are habits formed: Modelling habit formation in the real world. EJSP, 40, 998–1009. Open source