We did it. We survived the angriest three Presidential debates in the angriest Presidential campaign since Jefferson versus Adams in 1800. I’ve been reflecting on what we can learn as public speakers from the debates, and even at this brief remove there is already one clear lesson: preparation counts.

Basically, as we heard throughout the last couple of months, Trump didn’t prepare, and Clinton did. Trump even announced before the first debate that he didn’t want to prep too much because he was better winging it. So we ended up with a near-perfect experiment in the difference between a prepared candidate and an unprepared one.

Clients sometimes feed me the same line as Trump – I don’t want to rehearse because I’ll get stilted, over-rehearsed, and the result will look fake. I used to fall for that one, but not anymore. I now recognize it for what it is: an excuse to avoid preparation out of nervousness. It’s simply a way to postpone the evil day.

How did the great experiment turn out? Once the partisan dust settled, all three debates produced a clear winner, by the polls: Clinton.

Preparation matters.

Why? Because a debate on national television when the stakes are the presidency is an incredibly stressful, difficult public speaking moment. There are many moving parts. There are facts to remember, positions to explain, issues to attack and defend – the content. And then there’s the body language – the non-verbal communication. Political handlers typically do their candidates a disservice by focusing on content and largely ignoring the body language. They pressure their candidates to commit tons of stuff to memory – zingers, facts, and attack lines – when the body language is, at one level, far more important.

Why is that? Because when your content and your body language align, your message comes across, the one you’re speaking. When your body language and your content don’t align, people always believe the body language. So if you don’t prep that, you’re leaving the most important aspect of the debate to chance.

Rehearsing, therefore, helps at least some of the aspects of the debate become more familiar, less surprising. When a human being is surprised, he or she reacts defensively, and adrenaline spikes.

Your heart races, your palms get sweaty, the rest of you gets sweaty, you get a kind of tunnel vision, and your ability to think becomes similarly restricted.

You get dry mouth.

As a result, you drink water if it’s offered. And so Mr. Trump’s water drinking became a meme, while Mrs. Clinton never drank once. That made her look cooler under fire than Trump.

I dinged Clinton in an earlier post for her fake smile, but in fact, forcing a smile helps keep you positive, because we think consciously what we find our bodies doing. Clinton’s positive demeanor, from the very beginning, when she walked out each time with her head held high, her pace confident, and her pace measured and strong, contrasted clearly with Trump’s less confident entrance.

He should have rehearsed.

What else could he have done to boost his confidence? At the very least, he should have walked the room beforehand, so that the space could be more familiar to him – one less thing to surprise. Instead of planting old Clinton girlfriends, he could have put a friendly face at the back of the room, giving him someone to focus on to give him confidence and keep his head up, rather than looking down as he became tired and lost focus.

When the stakes are high and the performance nerve-wracking, you set yourself up to do your best by controlling as much as you can in advance, by rehearsing, and by role-playing everything you can. Winging it sets you up for failure.