I manifest kindness.

Kindness is bottlenecked by noticing. Most unkindness is not cruelty; it is a person on a crowded platform who genuinely did not see the pram at the bottom of the steps.

Which means the practical version of it is a kind of attention you can train. Look up more often than you need to. Once you have started seeing who is struggling with a door, you cannot stop seeing it, and the seeing does most of the work — the hands follow almost without being asked.