The only real thing that has helped me and had a lasting impact is when I made myself say exactly what I wanted to say, no word substitutions. If I stutter, so be it, I acknowledge it and move on with my day. If I let every stutter episode I have dominate my thoughts then I've already lost the battle. Combining this with speech therapy techniques to help me ease out those harder sounds has really improved my speech The key is to get used to these kinds of stressful situations, we'll only get better by doing it.