A few days ago I invited friends for a tabletop game day. I learned something about negotiating in the meanwhile.
One friend I invited said he wasn't sure if he will would come. I answered: "That's ok, if you come you will have a amazing day. "
After talking a bit more he said that he could maybe come but only for maximum a hour or so. I answered: "Awesome, if you come we will it make that hour well worth your time. We will make sure you have fun."
He came to the event and after an hour of having fun he said: "Ah well, I stay one more hour."
A day after the event he send me a message that he enjoyed it very much.
If I had at any moment said:"That's too bad. ", I don't think he would have come.
It seems to me that it was the positive language and the lack of judging or shaming for potentially not showing up did the trick.
Encouraging every small potential can lead to a "yes" I have noticed in this case
It seems that it is best to never close a negotiation as a lose yourself even when there seems almost no chance of getting the deal.