A compliment you thought of but didn’t say helps exactly nobody.

A good thought about somebody that stays inside your head has zero effect on the world. You noticed they were funny, or that the thing they made was genuinely good, and then some mixture of awkwardness and bad timing kept it in. They walked away without it, and the whole event took place entirely inside you.

Say the next one within about ten seconds of thinking it, before the window closes. It will feel slightly abrupt and that is fine, because nobody has ever been annoyed by this. Be specific. You will probably not find out what it did to their day, and it will have done something.