Real negotiation is not about forcing the counter-party to do what you want.
It’s about understanding him and what is holding him back from coming to your side.
It’s about taking away those obstacles and making it easy for him to accommodate you.
The alternative is trying to force him to come to your side, which just ends in digging-in and conflict.
Even if you win, you lose, because the other guy feels hard done by.
Better to put your energy into understanding what’s holding him back.