He writes, in a piece commissioned by Chipotle:
I even have tricks for slowing time—or at least my perception of it. At night I sometimes write down things that happened that day… Recording the quotidian details of my day seems to add hours a day to my life: I’m not sure why.
Another trick is to focus on some ordinary thing—the faintly geological strata of the insides of a burrito, for instance—and try to describe what I see.
Another: pick a task I’d normally do quickly and thoughtlessly–writing words for the side of a cup, say–and do it as slowly as possible. Forcing my life into slow-motion, I notice a lot that I miss at game speed. The one thing I don’t notice is the passage of time.
The last two points are what meditation and mindfulness are about. Observe the ordinary.
Here’s how Steven Johnson slows down time — he moved to a new physical place. In a new place, your status quo disrupted, and you’re forced to notice small details, which has the effect of making time pass more slowly.