If you think you're being humble, you're actually being proud. If you think you're doing a humble action - that's pride.
If a servant washes a king's feet, that's not humility - its just normal. But if a king washes another king's feet, that humble.
Put that another way: we have to think that we're something to think that we're humble.
Which is pretty gutting to me personally.
But it also points me to my Saviour - King Jesus, the truly humble servant, who served me.
May that same mind be in me, not considering position, but bending down to wash feet...