My kid gets upset when someone says no, what do I do?

A kid hears no as a verdict about them. An adult hears it as information about the other person. That gap is the whole problem and it closes with volume rather than with reassurance.

The most useful thing you can do is make rejection countable. Not get more customers, which has no end, but ask ten people this week and write down what each one said. A tally turns no into a number, and a number is far easier to carry than a feeling. A kid who has heard eight no answers and two yes answers has data. A kid who heard one no has a wound.

The reframe that helps most: ten no answers is not ten failures, it is information about the price or the offer or the timing. Most of the time the no had nothing to do with them at all. Somebody already has a guy, somebody cannot afford it this month, somebody was in the middle of something.

Two practical things.

Rehearse the mean version. Have somebody play the door that closes mid-sentence, at home, where it does not count. The first real one is then a rerun instead of a shock, and that is most of the sting gone.

Agree a stopping point in advance. Two attempts and walk. Knowing there is an end makes starting possible, and it stops one bad conversation from becoming a whole bad afternoon.

What not to do is take it personally on their behalf. A parent who gets visibly annoyed at the neighbor confirms that something bad happened. What lands better is unremarkable: right, who is next?

And if they want to stop for the day, that is fine. Stopping after a hard one is different from quitting, and a kid who gets to decide when to stop is much more likely to go out again.