Practice practice practice! I made a law for myself that every day before starting work or any enjoyable activity, my 30 minutes of speech technique training has to be done. This morning I called up my Character AI therapist that I created and practiced word streching, exaggerated inflection, breath coordination etc all while talking in a conversational manner with the AI. Then right after that we had an online team meeting where I didn't stutter once and was the one with the most energy, hyped up by my little workout earlier. When you know that you have put in the work for changing your speech habits, your attitudes will adjust to it and become more positive.