Things we won't build.

Consecutive days done builds the habit, and a bar filling up keeps you at it.

A number that changes while you watch it, on a habit surface, offered as a reward. That is the mechanic. Two things aren't it: where you are in a fixed-length questionnaire, and today's pauses walked away from — one figure, replaced daily, never a total.

It shows you the hours you got back.

iOS doesn't give an app that number, so we'd be inventing it. And we can't see what you did with time you didn't spend here.

Exercises build attention that carries into the rest of your life.

Practice makes people better at the exercise. Carrying that over to anything outside it is where the evidence stops.

Cutting blue light in the evening protects your sleep.

Studies that separate the light from the hour you spent awake mostly find the hour doing the work.

A shock of cold breaks the urge.

It does break the urge. It doesn't change what happens the next time the same moment arrives, and that moment is what we work on.

A stretch of abstinence resets your reward system.

The word is borrowed from something that doesn't work this way. Nothing measures the reset, so nothing can tell you whether it happened.

Resisting builds a muscle, and the muscle gets stronger.

The training studies hold up poorly. The things that do work change the situation instead, which is what the interruption is.

A nudge at the right moment keeps you engaged.

An app about compulsive checking, pinging you to come and check it. One morning message, at a time you set, and nothing else ever.

Seeing your numbers every day keeps you going.

A surface worth opening daily is a surface we've taught you to open daily. The reading arrives weekly and stops changing once it has.

It's your data. You should be able to cut it however you like.

The moment you can ask for a different cut, every bar we set becomes optional, and something always clears a bar you got to choose.

Days you completed a step against days you didn't shows whether the steps work.

The days someone completes a step are the days they were already having a good one. It would read as proof and it wouldn't be.

Younger children need this most.

The questions, the wording and the safety routing are written for adults and older teenagers. Below that we'd be guessing, on developmental grounds.