How do we stop the flight or fight response when we’re talking esp on words we may block on?

How do we stop the flight or fight response when we’re talking esp on words we may block on? I've heard that CBT is helpful. How would it apply to stuttering? Can we do this therapy by ourselves? I can feel like the adrenaline when I'm nervous or excited and it causes me to be on high alert, feeling like I'll slip on my words, stutter or block on words. As opposed to when I'm by myself and I feel relaxed, I don't feel like I'll stutter. We have to start somewhere safe right? But what if that somewhere safe doesn't transfer to over to normal situations?