Entrepreneurs, business leaders, and sales professionals often ask me the same question. How long--exactly--should I practice for a presentation? I've heard the question so often over the past 15 years of coaching, I have a ready answer. And it works.

First, I tell them that Dr. Jill Bolte-Taylor, a scientist who gave one of the top TED talks of all time, practiced her entire talk 200 times. Once their jaws drop, I give them the good news--you don't have to commit nearly that much time to stand out.

How many times should you run through your presentation?

The magic number is 10.

Assuming that you're delivering a standard business or sales presentation that runs anywhere from 20-45 minutes, you should strive to rehearse every slide from start to finish at least 10 times.

Give yourself at least ten days ahead of time to devote one practice session a day. If your pitch is 10 minutes or less, then you have no excuse. Ten rehearsals should be easy. You'll be amazed at the results. Here's why.

Practice will set you apart from your peers.

When I start working with speakers, I ask about their practice habits. Most of the time, they look at me with a blank expression. Rehearsing isn't part of their preparation. Oh, sure, they look through the slides and mentally go over their talking points--maybe once or twice. But they don't stand up and deliver the presentation out loud at least ten times.

A college graduate who had read one of my books contacted me to express his thanks. He applied my communication strategies for a job that he didn't think he was going to get. He didn't have as much experience as the other candidates going into the interview. 

This young professional stood out from the competition because he practiced for the interview many times over. He asked friends to pepper him with the type of questions he was likely to get. He recorded himself and watched his performance. When the day came, this college graduate was able to talk about the company's products better than the company's own employees. He estimates he went through at least 10 'mock interviews.' Preparation works. 

Practice will boost your confidence.

For my book on TED talks, I interviewed the famous Canadian astronaut and TED speaker, Chris Hadfield. In his now famous talk, Hadfield tells the story of going blind in space--a chemical in his spacesuit forced his eyes shut during a spacewalk. He remained completely calm, discovered the problem and fixed it. Hadfield stayed cool because he had practiced a spacewalk--and all of the things that could go wrong--hundreds and hundreds of times in simulators.

The same strategy applies to public presentations. Simulate real-world conditions. If you're going to stand in the real presentation, then stand in rehearsal. Put the slides up on the screen and advance the slides with a clicker in your hand. If you can convince one or two of your team members or someone you trust to watch one of your rehearsals, then do so.

One run-through isn't enough. You're still getting the hang of the flow and you haven't committed your key messages to memory yet. By the third, fourth, and fifth run-through, you're growing more confident. By the tenth run-through, you'll feel unstoppable.

Practice will improve your body language.

A little-known benefit of practicing your presentation at least ten times is the impact it will have on your non-verbal habits. For example, many people don't smile during a presentation. They look very serious. Steve Jobs, by contrast, always had a big smile on his face. He enjoyed the performance--and he practiced for his keynotes weeks ahead of time.

After rehearsing your presentation 10 times, you'll have committed your script or talking points to memory. It frees you up to think about your gestures, the pace of your delivery, and you can start to enjoy it. You'll actually begin to smile and enjoy the process. Once you do, your audience will have as much fun as you are.