We had hired a new senior executive. Soon after settling in, he began to share his concerns with me. He was doing so, he assured me, only because he loved working for us, and he was looking out for the wellbeing of the company. He reported to me, and at first, I appreciated his input.

Early on, he focused on small things, such as pointing out that he thought someone had spent more money than was warranted on a particular project. Then, he remarked on a couple of people who weren’t arriving at work on time. Later, he questioned whether we needed such a senior person in a given job, and couldn’t we get someone at a lower level to do the same job and save money?

Over time, he let me know he felt people were taking advantage of me. They didn’t appreciate how good they had it. I needed to be tougher.

I began to feel more anxious and suspicious, and others on our team seemed more tense. The buoyant, productive atmosphere that had characterized our culture for years, even in tough times, began to seep away.

Finally, another employee came to me and said that this executive had been complaining relentlessly to her, and that what he was saying didn’t seem warranted. Very quickly, I discovered he had rained these complaints on nearly everyone, treating each of his colleagues as a confidant and an exception to his otherwise withering assessments.

I felt at once angry and abashed. My most important job is to be our company’s Chief Energy Officer. In this case, I’d allowed myself to be unduly influenced by a destructive kind of energy, and then I had unconsciously communicated that energy to others.

Leaders, by virtue of their authority, exert a disproportionate impact on the mood of those they supervise. In this case, I was influenced simply by the strength of this executive’s negative feelings. Others in the office were more influenced by me, because I’m their boss.

Emotional contagion took hold. As the negativity spread, it drained the energy of our team and the company as a whole.

The negative emotions I “caught” temporarily overwhelmed my capacity to assess the facts at hand. Our company is in the midst of its best year ever, and across the board, people have been working hard and effectively. Our new executive’s concerns were vastly overstated.

How much do emotions matter in the workplace? Walk into any Department of Motor Vehicles and you’ll feel the impact of the prevailing mood instantly — a dense fog of sourness, irritability, and listlessness.

Walk into almost any Apple store and you’ll experience the opposite — a sense of aliveness and excitement that raises your energy (and makes you want to buy something).

I decided to let go of the negative executive, both because he’d lost the trust of our team, and because I didn’t believe he was capable of changing. The day I made the move, it was as if a cloud had lifted and the sun came back out.

So what lessons have I taken away from this experience?