How do you deal with sudden stammering during serious conversations, interviews, or exams?

How do you deal with sudden stammering during serious conversations, interviews, or exams? I usually speak fluently, but whenever I’m in a high-pressure situation like an interview, exam, or any serious conversation, I start stammering. It feels like I have the right words in my mind, but I just can't speak them out because my muscles freeze or block. It’s frustrating and affects my performance and confidence. Has anyone else experienced this? What strategies, exercises, or therapies helped you? Any advice would mean a lot.