Trying to affect our natural speech works in the short term, but from my experience talking is so engrained socially and psychologically that it’s very difficult to permanently change the natural (or unnatural) cadence of our speech. Plus from my work with stammerers, we don’t encourage this as a solution, it’s better to work on the voice you have than it is to work on a voice you don’t have. When it comes to advice, any speech school will practice breathing techniques, if you don’t know where to look, that’s a good place to start