If there’s one thing we humans are generous with, it’s our emotions. We share them constantly – in person, on stage, even online – whether we mean to or not. Emotions spread like infectious diseases, and for leaders talking to their teams, and speakers talking to a room, that’s both very good news and very bad news.

The good news first. If I’m genuinely excited about a big win or a new initiative, I can infect my team with that excitement just by talking to them about it. Speakers can do this too: we pass along our energy, our compassion, our grief, our anger, our joy – whatever the moment calls for – simply by feeling it ‘out loud’ in front of an audience.  Exactly how you do it is a matter of style, but begin with simply and clearly feeling it at the core of your being.

Now the bad news. If you’re not aware of your own emotional state – and not able to manage it –  you may end up sharing the wrong thing entirely. A nervous speaker who lets that nervousness show is dumping it straight on the audience, and nervous audiences don’t listen as well as relaxed ones.  They will close up instead of opening up. A leader who lets her rising panic about the company show is handing that panic to the whole team, right when she needs them focused, not spiraling.

This is why managing your emotions isn’t just optional for leaders and speakers – it’s the whole ball of wax. I know that sounds counterintuitive. Emotions just happen to us, right? How do you manage something involuntary? But you actually can learn to set emotional intent, the same way you’d set any other intent. 5-4-3-2-1, as Mel says! Leaders do it in high-stakes negotiations all the time – staying calm on purpose because it leads to better outcomes, or even losing their temper strategically, at exactly the right moment, to signal what really matters to them. Speakers do it walking out on stage, keeping their nerves in check because looking terrified in front of a crowd is rarely worth doing.  Audiences (unfairly!) interpret nervousness as lack of confidence in what you are saying.

And the research backs up just how contagious emotion really is. Stress spreads between people (Li et al., 2023), and so do emotions online.  A Facebook study of over a billion posts across two years found positive emotions in particular spread through our networks (Coviello et al., 2014). Rudeness is contagious in the workplace (Foulk et al., 2015), but so are kindness (Jung et al., 2020) and empathy (Zhou et al., 2024). Even risky behavior spreads, as we model what the people around us are doing (Suzuki et al., 2016).

It’s not just the big stuff, either. Yawning is contagious (Norscia et al., 2011), and so is shivering (Harrison et al, 2014) – researchers have even used yawning as an informal test for psychopathy, since psychopaths are less likely to “catch” a yawn thanks to lower empathy (Rundle et al., 2015). Smiling spreads too (Hess & Bourgeois, 1991), and, amusingly, so does mobile phone use (Maglieri et al., 2021).

So, while you are learning to get your emotions under new management, here’s an experiment to try:  take a day off from your mobile phone and just smile at people. Smile at your team.  Smile at people you pass on the street.  Smile at your barista.  The results may surprise you!