By remembering what you did at that moment in his life and repeat it.
He'll bounce back rather quickly, then you can push forwards from there.

Repetition and encouragement. If its something in particular — if you're speaking generally, that's more difficult.

Love. And take care of your own well-being. Skill sets come and go, for us, so I try not to overfocus on it.

Thanks GarryKellogg2!