I had a massive hang-up about this when I first started in the military. As an aircraft mechanic a huge part of my job is calling in discrepancies reported by aircrew to the Ops Center over a radio net. I think you can see the issue I'm getting at here. Now, my solution won't work for everyone, but I started adding a touch of an accent to my words. Nothing glaring or overt, just concentrating on an ever so slightly southern dialect. Focusing on getting the twang right helped me avoid the pitfall of overthinking and let the words come out smooth. Alternatively, I sometimes make my calls as Mickey Mouse. I do an awesome Mickey Mouse.