I try to focus on my speed, breathing or something else entirely to distract the mind. Although, if I focus on breathing too much, I find it can become difficult to breath correctly and often get a sore and winded chest. I've noticed that part of my stutter is due to doubt when I'm speaking or just not being able to form the word correctly and automatically restarting it which causes a stutter too. There are so many things that impact my speech, the biggest things I'd say is speed, breathlessness and a dry mouth.