Not long ago, I asked 100 CEOs attending a conference how many of them were currently involved in a significant business transformation. Nearly all of them raised their hands, which was no surprise. According to a study by BCG, 85% of companies have undertaken a transformation during the past decade.

The same research found that nearly 75% of those transformations fail to improve business performance, either short-term or long-term.

So why is transformation so difficult to achieve?

Among many potential explanations, one that gets very little attention may be the most fundamental: the invisible fears and insecurities that keep us locked into behaviors even when we know rationally that they don’t serve us well. Add to that the anxiety that nearly all human beings experience in the face of change. Nonetheless, most organizations pay far more attention to strategy and execution than they do to what their people are feeling and thinking when they’re asked to embrace a transformation. Resistance, especially when it is passive, invisible, and unconscious, can derail even the best strategy.

Business transformations are typically built around new structural elements, including policies, processes, facilities, and technology. Some companies also focus on behaviors — defining new practices, training new skills, or asking employees for new deliverables.

What most organizations typically overlook is the internal shift — what people think and feel — which has to occur in order to bring the strategy to life. This is where resistance tends to arise — cognitively in the form of fixed beliefs, deeply held assumptions and blind spots; and emotionally, in the form of the fear and insecurity that change engenders. All of this rolls up into our mindset, which reflects how we see the world, what we believe and how that makes us feel.

The result is that transforming a business also depends on transforming individuals — beginning with the most senior leaders and influencers. Few of them, in our experience, have spent much time observing and understanding their own motivations, challenging their assumptions, or pushing beyond their intellectual and emotional comfort zones. The result is something that the psychologists Lisa Lahey and Robert Kegan have termed “immunity to change.”