Every routine needs a minimum version or it will not survive a bad fortnight. Not the full hour — the two-minute one. Three slow breaths at a red light. A walk as far as the postbox. A boiled egg.
The point of the small version is not the physiology, which is negligible. It is that the thing never becomes something you used to do. Rebuilding an interrupted routine costs far more than maintaining a token one, and that is the whole argument for the two minutes on the days that deserve none.