You might think that you don’t have an alternative to your current negotiation. You have always an alternative! It might just be less attractive, but you have one. Invest time and energy to strengthen your alternatives as much as possible. Develop your BATNA (Best Alternative To Negotiated Agreement) early and actively.

With at least one attractive alternative, you are powerful enough to walk away, if you cannot reach an agreement where both sides win. Just imagine: How would it feel to negotiate and know, that you could walk away. You would have the option to negotiate with an alternative party on how to satisfy your interests. I bet, you feel relaxed and powerful.

You find more information in Getting To Yes by Roger Fisher, William Ury and Bruce Patton.