Years ago, I worked on a very difficult project. For one year, I put in long hours at the office, and even when I was home my mind was on the challenges to be overcome. It crowded out time for family and friends. My performance failed to reflect the effort being put in. After a year, I lost hope the project would be embraced by enough key stakeholders to enable it to meet its objectives, and eventually I left the firm because my health was suffering.

Although it was a painful experience, I learned a huge life lesson: We are hardwired for human connection, and when we crowd out time for connection, it sabotages our performance, happiness, and health.

Looking back on the experience, I now see that I had been lonely. You can be surrounded by people and interact with them throughout the day and still feel lonely. When you are in an environment that makes you feel controlled by others or that they are indifferent to you, one of the consequences can be loneliness. Why does this matter in the workplace? People who are lonely are more prone to self-defeating behaviors. They lose enthusiasm, energy, and optimism. They make poorer decisions. Loneliness, especially during times of high stress, frequently leads to ill health, including manifestations of suffering emotional health such as anxiety and depression.

Today, America and other nations around the world are experiencing an epidemic of loneliness, according to research studies that were further supported by research released by the insurance company Cigna earlier this year. Cigna surveyed 20,000 U.S. adults using the 20-question, scientifically validated UCLA Loneliness Scale. The average score was within the threshold of the scores considered to indicate loneliness.

A curious thing about loneliness is that often we don’t know we’re lonely. That was certainly the case with me. If you had asked me if I was lonely, I would have said no. And yet, if I had taken the UCLA Loneliness Scale during that season of my life, I’m certain I would have scored in the lonely range. Given our tendency to overlook or downplay these feelings, loneliness is the number 1 blind spot that is sabotaging people’s performance and holding them back from achieving their career hopes and dreams.

I believe loneliness is a primary reason so many people are struggling today. If you suspect this may apply to you, your family or friends, or the people you lead at work, join me from 2-3 p.m. ET on Thursday, July 12, for a free webcast I’m leading for the Association for Talent Development titled, “The Superpower of Human Connection and Perils of Isolation.” As part of the webcast, we will offer free resources and hold a drawing to win copies of my bestselling book, Connection Culture: The Competitive Advantage of Shared Identity, Empathy, and Understanding at Work.

I’ll also share some best practices and inspiring stories about leaders who created cultures that connected people and achieved great things.