The last message you send someone might be the last one. Don’t make it “k.”

Most conversations end without anybody knowing it was the end, so any exchange could turn out to be the final record between two people. That is not a reason to be solemn in every message. It is a reason to notice when you are being dismissive out of tiredness rather than because you mean it.

When you catch yourself sending a one letter reply, add a sentence. Not a speech, just something that sounds like you actually like the person. It costs five seconds and it changes what the exchange would look like later.