When you're a kid, you think about simple and exciting careers, like being a firefighter or ballerina, but then the practicalities of life shift your focus to something perhaps more pragmatic and maybe a little less adventurous. Still, statistically, by the age of 40, most people have changed their career at least once. Today you can become almost anything you want, and if the first career turns out to not be totally fulfilling, or you reach the pinnacle of success, you can start again to do something completely different.

Rick Kimball, a member of the Young Presidents' Organization (YPO), knows all about changing careers. After 26 years in investment banking, he was offered an opportunity to join Stanford University. He is a Fellow in their Distinguished Careers Institute exploring second careers focused on social change issues. The program offers a chance for successful people to step away from the day-to-day demands of life and marinate for a year in the vibrant intellectual and entrepreneurial environment of Stanford and Silicon Valley.

Although starting a second career can bring excitement and promise, it can also bring its own set of challenges if you are not ready. Here are some of Kimball's insights on how to make the process fruitful and rewarding.

1. Choose balance and meaning.

The early part of your working life is usually focused on building a stable lifestyle while accumulating wealth and reputation. However, ambitious careers can easily take over, hiding life's richer treasures. "I loved my investment banking career, but it didn't afford me a lot of free time for other endeavors and I spent much of my time rushing to complete work or to travel to a client," notes Kimball. "In my second career, I'm consciously structuring a more balanced, paced life so I can savor the many beautiful and profound aspects of the world in which we live."

2. Develop a growth mindset.

Kimball raves of his meeting with Carol Dweck, the Stanford professor and author of "The Growth Mindset." Dweck advocates holding a perspective where mistakes are not only accepted but celebrated as opportunities for learning. "In pursuing a second career, by definition, you are developing new skills," Kimball notes. "It's invaluable to have a curious mind and to be prepared to make mistakes as you build new capability and take on new challenges."

3. Find the Yin to your Yang.

Driven by societal generalities, many people are either labeled as analytical or creative. Some sheepishly follow one label without consideration for their capabilities in the other. Kimball had been steeped in the analytical until recently. "At Stanford, I took a course in Abstract Expressionism which opened my mind to new ways of seeing and understanding life," Kimball revealed. "In Walter Isaacson's recent book, 'The Innovator,' he describes how the greatest innovations have occurred when people can integrate a creative mindset with an analytical one. Leonardo da Vinci and Steve Jobs are great examples of people who have operated with an integrated analytical and creative mindset."

4. Enlist your own "personal board of directors."

Kimball insists you need people who help you grow, give you support and hold you accountable. He recounts his own experience. "One of the most valuable aspects of YPO is one's forum of eight or so peers, which serves as your confidential personal board of directors helping you work through key life issues personally and professionally. When I moved from New York to San Francisco to become a fellow at Stanford, I transferred from the YPO Manhattan chapter to a chapter in San Francisco and promptly joined a newly formed forum. The forum members are all in very similar places in their lives and have been invaluable resources to each other and as we have each worked through various life and career transitions. We've really supported each other to examine and explore new careers and new life phases."

5. Reframe your skill set.

People tend to narrow themselves with their work, but a second career opens new ways to leverage your expertise in new directions. Kimball shares his own realization on the versatility of his investment banking background. "Initially, I questioned the applicability of those very specific skills to a new career. On further reflection, I found that my experience selling at the CEO, CFO and board level was useful for all interactions with potential collaborators and partners."

Going deeper, Kimball was able to identify core attributes that were universally transferable. He shares, "Much of what I did in executing an IPO was to tell a company's story to prospective investors. I have come to the view that storytelling is key to transforming how people look at a given situation and, even more importantly, to finding the common passion that you share with others. I have found that a shared purpose connects people at a deep emotional level and is a precursor to creating flow in your life."

6. Be a generous connector.

The surest way for someone to bring you great opportunities is for you to bring opportunities to them first. Kimball explains, "I have found great joy in meeting interesting new people, expanding my network and connecting into new groups. In my investment banking days, I was maniacal about 'meeting velocity' or getting out to see the clients more often, which made all the difference to developing deeper relationships and ultimately winning business," says Kimball. "I applied the same strategy when I arrived at Stanford and tallied 250 meetings last year with professors, students, executives Silicon Valley and venture capitalists. This new network has opened up a multitude of new opportunities and has been a source of new learning and insight."

7. Dare to dream big.

What's the point of a do-over if you are going for the same level of success? Kimball shares how he restructured his thinking to make a difference the second time around. "Over the last hundred years, our life expectancy has increased dramatically from 50 years to 75-80 years. At age 52, I have probably 30 or more years to live, and I think I would be bored to tears if I just played golf for that period of time," notes Kimball. "With that much time ahead, I have the luxury to learn a new industry and develop new capabilities. Furthermore, the experience gained in my 52 years of life can be invaluable to solving some of the world's thorniest problems. I have been focused on helping transform the healthcare industry by changing the incentives for both physicians and patients. This is a gnarly problem to take on, but I have time to figure it out or at least figure out how I will contribute to the solution."

What can you now accomplish in your second career with your knowledge, experience and connections that would never have happened the first time around?

Each week Kevin explores exclusive stories inside the Young Presidents' Organization (YPO), the world's premiere peer-to-peer organization for chief executives, eligible at age 45 or younger.