I don't work out but I learned to metal scream about a year ago, which is extremely ab/diaphragm intensive. I've noticed that if I use the diaphragmatic support that I use for screaming in the context of regular speaking, I speak much more fluently. It's possible it is just a placebo, but I always wonder if there is something to it. I've recently been trying to develop a huge list of fluency techniques and this is one of them I've been trying to research