Why is replacing a habit easier than dropping it?

Taking a behavior out on its own leaves an unfilled gap behind. When nothing else goes into that gap, the same gap usually fills back up with the old behavior; this is why dropping something is harder than changing it.

Why does the gap fill back up?

A habit rarely stands alone; it is tied to a particular hour, a particular place or a particular situation. Something alongside the evening tea, a stop on the way home from work, or a movement before a meeting is really part of that context.

When the behavior is taken out, the context stays where it is. The hour comes round, the place is the same and the situation repeats; a gap with nothing to answer it is most easily closed by the old behavior. This is not a matter of willpower but of an unfilled place.

The gap may go unnoticed in the first days. Resolve is high at the start of a new decision and the absence is not felt; a few weeks later, when resolve returns to its ordinary level, the same gap makes itself known, and most giving up happens at exactly that point.

What does replacing mean?

Replacing means settling on another behavior that serves a similar function in the same context. Something else alongside the evening tea, another route instead of the stop on the way home, or another movement before the meeting.

It matters that the new behavior happens in the same place and at the same moment as the old one. A replacement placed in the morning or on another day does not fill that gap, because the gap sits at a particular point in time and stays there.

The replacement also has to be as easy to reach as the old behavior. A replacement that needs preparing, needs buying, or needs thinking about every time drops out on the first busy day, and the gap opens up to the old behavior again.

How do you choose the replacement?

That the replacement can actually be carried out matters more than how good it is. An option that is on hand, ready and needs no extra preparation lasts far longer than a better option that has to be prepared every time.

The replacement also has to meet the same need. If a behavior is done for the taste, something with taste goes in its place; if it is done to take a break, a short break goes in its place. When the need is read wrong, the replacement does not hold.

What the need is becomes clear after a few days of watching. Looking at what was done just before that moment, where you were and how you felt usually shows directly which gap the behavior was filling.

When do you actually need to drop it?

Not every habit calls for a replacement. Some behaviors fade on their own once the surroundings change; a bowl taken off the table or a package moved to another room gives the same result with no replacement at all.

Looking for a replacement for a habit that a change of surroundings solves brings an unnecessary burden. The surroundings are tried first; if the behavior still repeats, then a replacement is set up.

One advantage of changing the surroundings is that it lasts. A package moved once is not moved again every day; a replacement, by contrast, has to be kept on hand and renewed from time to time. So the route that needs the least upkeep is tried first.

How long does the change take to settle?

How quickly the new behavior settles depends on the number of repetitions and on how often the context comes round. In a context you meet every day the change takes hold sooner; in a situation that comes once a week, the same result takes far longer.

Going back to the old behavior in between is ordinary and does not invalidate the process. A day you go back is not a failure but a sign that the replacement was not ready enough in that context; once the replacement is made easier, the change carries on from where it left off.

This is why trying to change several habits at once rarely works. Each change needs its own context and its own replacement; taken one at a time the settling period is longer, but what stays is noticeably greater.