Grant graciously what you cannot refuse safely, and conciliate those you cannot conquer.

When you have to concede, how you concede is the only part still in your hands. A grudging yes gives away the same ground and earns none of the goodwill, so you pay the price twice, while a generous one leaves the other person something to reciprocate later. The same reasoning applies to opponents you cannot beat. If they are going to be there regardless, an enemy is more expensive than an accommodation.

Look for the concession you are currently making slowly and resentfully. Make it properly and quickly instead, and let the manner of it buy you something. You are giving up the ground either way.