This happened to me when I was put on SSRI's. It was completely gone. I ultimately went off them though for good, as I could not get past the side effects. Having no libido was enough to get me off them completely. It was nice being able to talk fluently, but I'd rather have a stutter than a fucked libido. Sounds like it really worked for you, that's great. I can definitely see how fitness and getting adequate sleep can make an impact on stuttering. If I don't get enough sleep I'm generally useless haha.