I definitely recommend David Goggins overall, he's a great dude who still inspires millions to this day, his book is called Can't Hurt Me if you're interested. One other thing I noticed when speaking is that I usually start blocking when I think about it consciously. When I don't pay attention to my speech at all, things just come and go naturally. It's only when I have a burning desire to say something that I start to completely tense up and block, after I've consciously reminded myself that it will most likely come up, this is something I have to try and eliminate, because that's where 90% of my blocks come from. As for my acquaintances, they told me they just "grew out of it", and I really find that odd, considering many adults here share their experiences of stuttering well into their 30s. It proves that all of us process this differently, and something that might work for one person, may not work for another. I suppose they developed different mentalities, or an overall "don't-really-give-a-shit" attitude about it, and it went away naturally as a result of that. Ironically, that does tend to work sometimes, but it's not something that you can keep doing for the rest of your life, and it will alienate you from others.