Try recording a two minute video of yourself talking on a random subject (you can use this site to generate it for you (also good for generating titles for posts (and no, I didn’t use it for this one)): https://capitalizemytitle.com/random-topic-generator/) without (and here’s the key) saying the um (or urm) sound. Nope, not even once.
Easy? You reckon! Well, I couldn’t do it. 😦