I found some specific things to help. Like taking a quick breath before I start speaking. It might be a noticeable breath/noise sometimes but it works for me. Also I push my tongue to the roof of my mouth before a word or sound that I know I will struggle with and it acts as my trigger to spit it out more fluently. I have no idea why it works but it does. I’m in my mid 40s and just stumbled upon these things over the years.