This is a Lexicon entry: the mechanism, when it shows up, and the countermeasure. The full correction, with real-world cases and the audit prompt, hasn't been written yet.
Definition
The tendency for a behaviour that is already in progress to continue with less effort than initiating the same behaviour from rest - a psychological analogue of physical inertia. Beginning a task is the costliest cognitive step; once started, continuation is relatively cheap. This is why "just two minutes" strategies (commit only to starting, not finishing) are effective habit formation tools. It also explains why interruptions are so costly: they do not just pause work, they eliminate accumulated behavioural momentum.
When it shows up
Long-running routines under sudden disruption: an exercise habit that survives a chaotic week, a team process that keeps running despite a distracted manager, a daily practice you keep on a day you don't feel like it. Momentum is strongest in fixed contexts - same time, same place, same trigger - built up over a long history, not in behaviours you just started.
Failure mode
Assuming momentum travels with the behaviour rather than the context: relocating a working routine to a new time, place or trigger resets its resistance to disruption even though the habit feels unchanged so it collapses at the first obstacle. The mirror failure: treating a brand-new habit as already resistant to disruption and skipping the deliberate effort its first fragile weeks require.
Countermeasure
Protect an established routine by holding its context fixed - don't move the time, place or trigger unless you're prepared to rebuild its resistance from near zero. For a new routine, anchor it to one stable context and hold that context constant through the early weeks, rather than relying on repetition count or motivation alone.
Related traps
Also connected in the map3 more, locked
Credit & first seen
DiscoveredNevin, J.A., Mandell, C.&Atak, J.R. (1983).The analysis of behavioural momentum.Journal of the Experimental Analysis of Behaviour 39(1), 49-59 source ↗
Also revealed
Entry #113 of 631 in The Lexicon · see the full Lexicon