When a habit starts to feel easy, most people treat that as success. The 18th-century Scottish philosopher David Hume noticed something uncomfortable about this: familiarity doesn't just make actions easier — it makes them *invisible*. We stop perceiving what we're doing because custom, as Hume put it in his Treatise of Human Nature, 'renders the transition so smooth that we are scarce sensible of it.' The problem is that an invisible habit can drift. The form remains but the substance quietly empties out — you're still going to the gym, still writing in the morning, still logging your food, but the quality of engagement has hollowed. What Hume's insight suggests, when pushed into practice, is that the point of friction in a mature habit isn't building it — it's periodically *de-familiarizing* it enough to see it again. A small deliberate variation (a different route, a changed sequence, a new constraint) doesn't disrupt the habit; it restores your ability to perceive it. That perception is what keeps it alive rather than merely automatic.

Pick one habit you'd describe as 'solid.' What is the last specific change you made to how you execute it — and what did that change reveal?

Drawing from Scottish Empiricism combined with perceptual psychology of habituation — David Hume — A Treatise of Human Nature (1739), Book I, Part III, Section XIV