When you speak to someone, how long do they listen to what you're saying? Three minutes? One minute? Ten seconds? Start a timer for these lengths of time and sit still without doing anything for that amount of time. It's hard, isn't it?
Every word you say in a conversation has an attention cost. Once you've spent all the attention your listener has, you'll see their face go blank as their mind begins to wander.
So, if you want someone to listen to you, say fewer words.