Back in college, my MBTI was INFJ. After working for a few years, in which my first job involved talking to clients, my MBTI changed. Right now it is 50-50 introvert and extrovert. I could say that the transition from introvert to ambivert is mainly due to work where I'm required to talk to clients. It put a pressure (not necessarily bad) on me, thus I had to change my personality. Looking back, I think it is actually a good change. I still consider my self as an introvert, I still dislike large gatherings. But at least now I'm flexible to switch to being outgoing when needed to. Edit: forgot to mention, I still do stutter. But my method is to use synonyms or to reverse the sentence structure. And sleep 8 hours a day.