Laura Seitz, Deseret News
Clayton Christensen is photographed at the Triad Center in Salt Lake City on Oct. 29, 2010.

Editor's note: From "How Will You Measure Your Life?" by Clayton M. Christensen 2012 by Clayton M. Christensen, James Allworth, and Karen Dillon. Reprinted courtesy of Harper Business, an imprint of HarperCollins Publishers.

On the last day of the course that I teach at Harvard Business School, I typically start by telling my students what I observed among my own business school classmates after we graduated. Just like every other school, our reunions every five years provided a series of fascinating snapshots. The school is superb at luring back its alumni for these events, which are key fund-raisers; the red carpet gets rolled out with an array of high-profile speakers and events. My own fifth-year reunion was no exception and we had a big turnout. Looking around, everyone seemed so polished and prosperous — we couldn't help but feel that we really were part of something special.

We clearly had much to celebrate. My classmates seemed to be doing extremely well; they had great jobs, some were working in exotic locations, and most had managed to marry spouses much better-looking than they were. Their lives seemed destined to be fantastic on every level.

But by our tenth reunion, things that we had never expected became increasingly common. A number of my classmates whom I had been looking forward to seeing didn't come back, and I had no idea why. Gradually, by calling them or asking other friends, I put the pieces together. Among my classmates were executives at renowned consulting and finance firms like McKinsey & Co. and Goldman Sachs; others were on their way to top spots in Fortune 500 companies; some were already successful entrepreneurs, and a few were earning enormous, life-changing amounts of money.

Despite such professional accomplishments, however, many of them were clearly unhappy. Behind the facade of professional success, there were many who did not enjoy what they were doing for a living. There were, also, numerous stories of divorces or unhappy marriages. I remember one classmate who hadn't talked to his children in years, who was now living on the opposite coast from them. Another was on her third marriage since we'd graduated.

My classmates were not only some of the brightest people I've known, but some of the most decent people, too. At graduation they had plans and visions for what they would accomplish, not just in their careers, but in their personal lives as well. Yet something had gone wrong for some of them along the way: their personal relationships had begun to deteriorate, even as their professional prospects blossomed. I sensed that they felt embarrassed to explain to their friends the contrast in the trajectories of their personal and professional lives.

At the time, I assumed it was a blip; a kind of midlife crisis. But at our twenty-five- and thirty-year reunions,the problems were worse. One of our classmates — Jeffrey Skilling — had landed in jail for his role in the Enron scandal.

The Jeffrey Skilling I knew of from our years at HBS was a good man. He was smart, he worked hard, he loved his family. He had been one of the youngest partners in McKinsey & Co.'s history and later went on to earn more than $100 million in a single year as Enron's CEO. But simultaneously, his private life was not as successful: his first marriage ended in divorce. I certainly didn't recognize the finance shark depicted in the media as he became increasingly prominent. And yet when his entire career unraveled with his conviction on multiple federal felony charges relating to Enron's financial collapse, it not only shocked me that he had gone wrong, but how spectacularly he had done so. Something had clearly sent him off in the wrong direction.

Personal dissatisfaction, family failures, professional struggles, even criminal behavior — these problems weren't limited to my classmates at HBS. I saw the same thing happen to my classmates in the years after we completed our studies as Rhodes Scholars at Oxford University. To be given that opportunity, my classmates had to have demonstrated extraordinary academic excellence; superior performance in extracurricular activities such as sports, politics, or writing; and significant contributions to their communities. These were well-rounded, accomplished people who clearly had much to offer the world.

But as the years went by, some of my thirty-two Rhodes classmates also experienced similar disappointments. One played a prominent role in a major insider trading scandal, as recounted in the book Den of Thieves. Another ended up in jail because of a sexual relationship with a teenager who had worked on his political campaign. He was married with three children at the time. One who I thought was destined for greatness in his professional and family spheres has struggled in both — including more than one divorce.

I know for sure that none of these people graduated with a deliberate strategy to get divorced or lose touch with their childrenmuch less to end up in jail. Yet this is the exact strategy that too many ended up implementing.

I don't want to mislead you. Alongside these disappointments, there are many of my classmates who have led exemplary personal lives; they have truly been an inspiration to me. But our lives are not over, and the lives of our children are just now unfolding. Understanding what causes the problems that trapped some of my classmates is important not just for those who have come off the path that they had planned to follow but for those whose lives are still on the right pathas well as those whose journeys are just beginning. We all are vulnerable to the forces and decisions that have derailed too many.

I am among those who have been fortunate so far — in many ways due to my wonderful wife, Christine, who has helped us see into the future with remarkable prescience. It would be folly for me to write this book, however, to proclaim that everyone who replicates the decisions we have made will be happy and successful, too. Instead, in writing this book, I have followed the approach that has characterized my management research.

I have engaged my students in the quest as well. In my MBA course, Building and Sustaining a Successful Enterprise, we study theories regarding the various dimensions of the job of general managers. These theories are statements of what causes things to happen — and why. When the students understand these theories, we put them "on" — like a set of lenses — to examine a case about a company. We discuss what each of the theories can tell us about why and how the problems and opportunities emerged in the company. We then use the theories to predict what problems and opportunities are likely to occur in the future for that company, and we use the theories to predict what actions the managers will need to take to address them.

By doing this, the students learn that a robust theory is able to explain what has and what will occur across the hierarchy of business: in industries; in the corporations within those industries; in the business units within those corporations; and in the teams that are within the business units.

In the past several years, on the last day of my class after I've summarized what so frequently happens in the lives of our graduates, we have taken the discussion a step further, plumbing to the most fundamental element of organizations: individuals. For this discussion, rather than use businesses as the case studies, we use ourselves.

I participate in these discussions with more history than my students do, but I follow the same rules. We are there to explore not what we hope will happen to us but rather what the theories predict will happen to us, as a result of different decisions and actions. Because I've been present in these discussions over many years, I've learned more about these issues than any one group of my students ever has. To even the score with them, however, I have shared stories about how these theories have played out in my life.

To help structure this discussion, I write the theories we have studied along the top of the chalkboard. Then I write three simple questions beside those theories:

How can I be sure that

I will be successful and happy in my career?

My relationships with my spouse, my children, and my extended family and close friends become an enduring source of happiness?

I live a life of integrity — and stay out of jail?

These questions might sound simple, but they are questions that so many of my classmates never asked, or had asked but lost track of what they learned.

Year after year I have been stunned at how the theories of the course illuminate issues in our personal lives as they do in the companies we've studied. In this book, I will try to summarize some of the best of the insights my students and I have discussed on that last day in class.

IN THE SPRING of 2010, I was asked to speak not just to the students in my own class but to the entire graduating student body. But that's not the only way things were a little different that day. Standing at the podium with little hair as the result of chemotherapy, I explained that I had been diagnosed with follicular lymphoma, a cancer similar to that which had killed my father. I expressed my gratitude that I could use this time with them to summarize what my students and I had learned from focusing these theories on ourselves. I spoke about the things in our lives that are most important — not just when you are confronting a life-threatening illness, as I was, but every day, for every one of us. Sharing my thoughts that day with the students about to make their own way in the world was a remarkable experience.

James Allworth, who was in my class that semester and in the audience that day, and Karen Dillon, who heard about my remarks in her position as editor of the Harvard Business Review, were both extremely moved by the topic. I later asked them to help me convey to a broader audience the feeling people had that day in Burden Hall on the Harvard Business School campus.

We are from three different generations and have completely different beliefs informing our lives. James is a recent business school graduate, who assures me that he is an atheist. I'm a father and grandfather with a deeply held faith, far into my third professional career. Karen, the mother of two daughters, is two decades into a career as an editor. She says her beliefs and career fall someplace between us.

But the three of us are united in the goal of helping you understand the theories we share in this book because we believe they can sharpen the acuity with which you can examine and improve your life. We've written in the first person, my voice, because it's how I talk to my students — and my own children — about this thinking. But James and Karen have truly been coauthors in deed.

I don't promise this book will offer you any easy answers: working through these questions requires hard work. It has taken me decades. But it has also been one of the most worthwhile endeavors of my life. I hope the theories in this book can help you as you continue on your journey, so that in the end, you can definitively answer for yourself the question "How will you measure your life?"