Maybe this is splitting hairs over definitions, but I don't think getting lost in trains of thought (like OP) or the "quiet reflection" that you did is doing nothing.

When I think of doing nothing, I think of doing nothing. No catching up on thoughts we don't have time for, no chasing ideas, just nothing. It's really hard for a few minutes, let alone 30, let alone 24h!

Part of this is that I think of quiet reflection as healthy, if not necessary, and thus, it is something.