I am mindful of other people and their feelings.

One version of this isn't kindness at all, and it's hard to tell apart from the inside: scanning a room constantly for signs of displeasure, then adjusting yourself until they're gone.

Being attuned to people and being unable to bear their disappointment are separate conditions. The first notices a friend has gone quiet and asks about it. The second notices, assumes it's about them, and starts apologising for something nobody mentioned.

Kind people say difficult things sometimes. Agreeable people don't, and the difference surfaces years later, in who was ever actually told the truth about anything.