Thank you for sharing. I think it's a good theory but I don't think it exactly applies to me. I went over the topic of concentration in this comment: [https://www.reddit.com/r/Stutter/comments/jupzmc/that\_feeling\_of\_running\_out\_of\_fuel/gceybin](https://www.reddit.com/r/Stutter/comments/jupzmc/that_feeling_of_running_out_of_fuel/gceybin/?utm_source=reddit&utm_medium=web2x&context=3) ​ I think tiredness comes from a variety of sources, not necessarily related to speech. e.g. simply the fact that I'm having a social interaction, which needs listening, paying attention to my counterpart, etc. ​ If I were to spend the whole day with a friend probably I'd end up very tired. I don't think that happened to me just a couple years ago when I felt fluent *and* energetic. ​ So I wonder if I could improve something in my lifestyle, my brain is lacking some nutrient, etc.