This article was originally published in strategy+business.

The trick is to remain focused on your purpose and surround yourself with good people.

He’s the guy next door. He’s a generous, gregarious, and hard-working dad with two kids. But because he made his living selling drugs, he’ll be in a federal prison for the next 20 years—an absentee player in his former life.

We’ve all heard this kind of anecdote before; it’s the same story with different names: Jeffrey Skilling, Bernard Madoff, Nick Leeson. Each tale is shocking in scope and scale. Each one continues to amaze, leaving those of us living honest, simple lives shaking our heads and asking, “How could they be so stupid?”

But even as we ask the question, we know the answer. We are all that stupid. Clayton Christensen, a professor at Harvard Business School and author of How Will You Measure Your Life?, was a classmate of Jeffrey Skilling and remembers him as a “good man” who worked hard and loved his family. In his book, Christensen recalls a litany of “decent” classmates and colleagues who “had plans and visions for what they would accomplish,” but who instead have ended up divorced, living separately from their kids, hating their jobs, and in jail.

Considering that we all have the potential to inflict harm on ourselves and those we love, it’s important to continually reflect on how to keep the worst in us from getting the best of us:

1. Hang out with good people. Jim Collins, author of the book Good to Great, recommends forming a “personal board of directors,” consisting of people you admire—not for what they have done but for who they are. Since we can be pulled up or down by the people around us, Hitendra Wadhwa, a Columbia University professor who teaches the popular Personal Leadership and Success course, encourages his students to reengineer their “social environment so that it supports you in moving toward, rather than away from, your ideal self.”
   
2. Stay focused on your purpose. Collins believes it’s impossible to have a “meaningful life without a meaningful quest done with people we love doing it with.” Work with your “board of directors” to discover your purpose. Using Collins’ Hedgehog Concept, ask yourself three questions: “What am I passionate about? What can I do better than most other people? What can I get paid to do?” Once you have an overarching purpose or strategy, Patrick Lencioni, author of The Advantage, recommends defining a temporary (six- to 12-month) rallying cry to focus your energies on what is truly most important, right now. And once the rallying cry has been identified, further clarify it “by defining the objectives which will make accomplishing it possible.”
   
3. Be mindful. Achieving oh-so-lofty goals requires, in part, anchoring yourself in daily disciplines to stay connected and committed to your “inner code” and resist unhealthy societal norms, according to Wadhwa. As examples of daily disciplines, he cites Winston Churchill’s practice of reflecting on the worthiness of his day as he fell asleep each night; Steve Jobs’ morning ritual of planning each day as if it was his last; and Nelson Mandela’s letter writing, which helped him clarify his values and transform his life during his time in prison. Similarly, Christensen recommends making decisions by mentally playing the movie of your life forward, and understanding that the “marginal cost of doing something ‘just this once’ always seems to be negligible, but the full cost will typically be much higher.”
   
4. Remain humble. Through his research, Collins’ has found that the mighty fail when success is followed by hubris. Arrogant leaders confuse power with excellence, use past success to predict the future, and conflate good intentions with good decision. Great leaders embody humility so that they can work with others to “confront the brutal facts,” Collins says.
   
   We all have the motivation and capacity to live lives worth living. Wadhwa believes that there are “core hungers that all human beings possess, which is to cultivate character, derive meaning from life, master one’s inner forces, grow and become better people, and engage in loving relationships with the people in our life.” It’s possible, he adds, to do all this while pursuing success.
   
   The most eloquent answer to the “How could they be so stupid?” question was given by C.S. Lewis who wrote, “The safest road to Hell is the gradual one—the gentle slope, soft underfoot, without sudden turnings, without milestones, without signposts.” Fortunately, few of us will be stupid enough to end up in prison. But unless we are very, very careful, we can easily become trapped in a prison of our own making—decision by stupid, distracted decision—until we too become absent from the lives we were meant to live.

This article was originally published in strategy+business.