There are a few approaches that might help. You could look up soft contacts (aka light articulatory contacts). Another approach that I find helpful is prolonged speech”. I used to fixate a lot on particular sounds and spend time stuttering on those - but more recently I’ve realised that when I stutter on an “m” or whatever sound there’s actually more going on. It’s to do with the complexity of the whole phrase that comes after and not just that one sound. It sounds unlikely when you are having so much trouble with that one sound but try this: - practice stretching out some words (I don’t mean leave longer gaps between the words but the words themselves should be elongated). You can start by doing this in an exaggerated way to get the hang of it. - practice prolonging words in a less exaggerated way - when you are about to speak in a real life conversation, deliberately prolong the sounds slightly Just my own experience but I’ve been surprised how much prolonged speech can help.