That happens to me, too. I've found that on days when I feel confident and energised I stutter less than on days when I'm run down and feeling overwhelmed. So now I focus on getting good quality sleep to ensure I'm rested. I also get good exercise and eat well to feel good. I also work on my self confidence and self worth. By staying on top of these, I improve my fluency. It's amazing what good sleep, exercise, diet and mental attitude can achieve.