I was a Ph.D. student in psychology participating in a seminar with two very senior professors, both authors of multiple fairly important books. I was rattling on about something I felt strongly about — some theory or other I had recently discovered — and had dug in my heels, more out of anxiety than conviction. I was trying to force agreement. A couple of the other students took me on and started arguing with me.
On of the famous professors said ‘Hang on, can’t you see David has strong feelings about this? This isn’t just academic to him. Let him talk.” The other professor nodded.
I had been struggling to control the seminar. These brilliant guys directed all the future psychologists to be aware of the impact of strong feelings on accuracy and civil discourse, a good lesson. As for me, I felt respected and heard, and suddenly lost all need to win, or convince, or prevail. That was an enduring life lesson for me.
Exactly the same principles apply to a client who struggles to control. Showing regard, deep respect, and kindness will take the wind out of his sails.