you cant promise a child something, disappoint him, then hand out sweets by the dozen hoping that would stop the wailing and the tears.
once you make a promise, you should see it through, but if you cant, you should feel the child's pain as your own, and bear the weight of guilt.
no amount of sweets can make up for dashed hopes or broken promises, only a resolve to not make the mistake again with sincerity can make amends.
if you were not confident, you should have kept your mouth shut. if it's said on a whim, that's even worse.

and you know what? this doesnt only apply to kids.