Vowels always make me trip up. Here are some things I’ve used over the years and still do: If the vowel word isn’t first in the sentence, combine it with the last world and make one big one. “The animal” becomes “Theanimal”. It’s easier to sneak the vowel in that way without having to focus on it. If there’s no word before it, make one. Like a subtle “hmm” or “umm” “so”, etc. Also a general ease into the vowel. Try and get it out in one big exhale. Gets easier and easier the more you do this one. Best of luck comrade!