Because it is most of the time and this is coming from someone who used to have a servere stutter now brought down to very mild. Few questions first. When you're alone or talk with pets do you not stutter or barely stutter? When you sing do you stutter? If yes then it is mental, something that we thought ourselves to do from a very young age or due to some trauma or something which is still mental. If you stutter less with certain people or more when feeling anxious or nervous it is MENTAL. And of course we make it worse mentally by being negative toward ourselves, always thinking about it, we make our lives revolve around it, when you put that much attention and focus on something it will get worse. I won't tell you how to help it because everyone is different and use stutterers are stubborn af, so ill just tell you my experience with helping myself which was a lengthy process that took months of sheer will everyday. I reached the point of suicidal thoughts, saying ill never get married, no woman will ever love me, no one will ever respect me or take me seriously, life sucks ill never be normal, why is this the only handicap people are allowed to make fun of? See a pattern? All negative. What helped ME was loving myself for who I was even when I felt no one else would ever even try. I became my own best friend and supporter, always telling myself it will be ok. After I converted negative reactions to my stutter with positive reactions it was easier to slowly wean off even thinking about it. For example, standing in line waiting to order food we begin overthinking, getting anxious what will happen, trying to choose a menu item that will be easier to say not even getting something we want to eat to avoid stuttering. Who gives a fuck. The sooner you give it less attention the less you will stutter. Now this isn't gonna happen overnight, we've wired our brain to obsess over this stutter and with good reason it does really suck and it ruins a lot of opportunities. But the only way to improve is to take it day by day with sheer will. And we can do it, living with stutter causes us to take in some of the greatest mental pain imaginable making us stronger than we know. Also train and push yourself to maintain eye contact. As a fellow stutterer I already know we never make eye contact especially mid stutter. The bravest thing a stutterer can do it stutter and maintain eye contact like a fucking boss. Don't look away, your stutter wins. Once you get used to doing that it will get better. Start small though. It's a long long long process to rewire the mind, start by being positive and work your way up. We have no other choice. Good luck my brother 🙏