A crowded hallway can be the loneliest place. Look for the people looking at the floor.

Being surrounded is not the same as being with anyone, and a busy corridor can make that gap worse rather than better. Everybody has somewhere to be and somebody to walk with, and if you have neither, the crowd is the thing that makes it visible. The people reading the floor are usually doing exactly that arithmetic.

You can change somebody’s afternoon with very little. Say their name in the corridor, walk the same direction for thirty seconds, save a seat and tell them it is theirs. You do not have to fix anyone’s situation to be the reason it was not a completely silent day.