Even when they're not speaking out loud.
Preparation is critical to ensuring that your presentation goes according to plan. But don’t let your plan get in the way of a flexible and responsive communication.
Sometimes you will learn over the course of a presentation that what you prepared to say isn’t actually what would best serve your listeners. Your content may turn out to be too detailed, too general, or just not especially relevant.
Sometimes your listeners will tell you what they need with their words. If not, you may have to glean it from their body language or facial expressions. In any case, when you become aware that your audience would benefit from something other than what you prepared, resist the urge to forge ahead with your material anyway — even though you may have worked very hard on it. Instead, leave the safety of your preparations and forge ahead with what will make best use of your audience’s time.
This shift will come naturally if your primary focus is on your listeners and what they need, rather than on yourself and what you want to say.