First time I made improvments reducing my stutter was probably at 16, I had a group of friends I felted conformtable with so that made me talk more (I also tried to talk more as a sot of challenge to myself), second time was the same thing just with a different group (I wa probably 19-20) and with this group I was the main "organizer" (I would say "leader" but that makes me cringe a bit) meaning that most of the times no one was calling the group to hangout at place X or Y, and when we were toghether everyone was on the "I'll do what everyone wants to do" attitude wich always ended on us doing nothing so I stepped up to say "Let's do this or that" so this dynamic made me talk even more. Last time I noticed improvments in my stutter was this year since I started to practice diction exercises to imrpove my fluidity, the type of exercises theather people and public speakers practice