By Mark Miller

(Reuters) - The Great Recession has left millions of midlife Americans up a creek without a paddle. Having lost jobs at the peak of their careers, they must find new work for the second half of their lives. Many will likely need to reinvent their careers -- and may consider themselves too old to embark on something new.

Mark Walton begs to disagree.

The former CNN correspondent transformed his own career 20 years ago by becoming a Fortune 100 leadership consultant. Now 61, Walton has spent the past five years studying people who transformed their careers successfully in their 50s or early 60s, and invented new ways of working that extended into their 70s, 80s or even 90s.

A growing body of neuroscience research suggests that old dogs can learn new tricks, and that they can do it better than the young ones.

Walton elaborates on how the scientific research connects with the real life experiences of successful midlife transformations in his new book , "Boundless Potential: Transform Your Brain, Unleash Your Talents, Reinvent Your Work in Midlife and Beyond" (McGraw-Hill).

He concludes that our brains are wired not for retirement, but for constant reinvention. And that seniors can tap extraordinary creative and intellectual powers in the second half of life -- if they put in the required work.

SOME WORK REQUIRED

"The mature brain may lose some of the processing speed and accuracy that the younger brain has, but it isn't inferior," says Walton. "The mature brain is just organized differently. And especially when it is adequately challenged, it keeps growing and developing new strengths and assets that the average younger brain cannot compete with because of the reservoirs of knowledge that we have -- what we sometimes call wisdom."

"The most significant factor influencing this process is how -- and whether -- we challenge our brains in midlife and beyond, by aspiring to and tackling higher levels of accomplishment," he says. "Simply put, our brains work best when worked hard. Doing this literally rewires and reorganizes the brain and allows new creative, intellectual and social intelligences to emerge and be put to work."

Walton draws on seminal research on aging brains, most notably the work of the late Dr. Gene Cohen, a pioneer in geriatric psychiatry. Cohen, who died in 2009, played a key role in revolutionizing the conventional wisdom about aging, and was well-known for his research on the effects that creativity can have on older adults and the aging process.

He also draws inspiration from the work of management guru Peter Drucker, who foresaw the shift to a knowledge economy and how it would transform careers.

"Drucker wrote in the 1990s -- when he himself was in his 90s -- that in the new millennium, one of three things would happen when we reached our 40s or beyond," Walton says.

"Either our careers or financial lives would be derailed by rapid, unforeseen events, or we'd stay in the same job too long and burn out. Or, we'd finally retire only to find ourselves bored into an early grave. Why? Because we're all knowledge workers in the 21st Century, and the brains of knowledge workers are never really finished or worn out."

A SECOND INTEREST

So, the implication is that extending success beyond the first half of life requires knowledge workers to develop a second major interest, and create their own work based on that interest. In other words, in the post-industrial information age, we need to manage ourselves."

Walton's study of successful midlife reinventors pointed toward a pattern -- three steps all successful reinventors seem to take.

"No matter what their previous profession had been, the first step was to examine their lives up to that point, and to ask themselves, 'Given what I've seen and experienced thus far, what is it that really fascinates me? What tugs at my mind and heartstrings? What truly lights me up?'"

The second step is to translate that personal fascination into action -- real-world work that the career changer would deeply enjoy and feel empowered them for success.

The final step is to find a structure for the new work, whether it involves starting a new business or nonprofit, or creating new roles or careers.

Walton began his own career at age 15 at a news talk radio station in Hartford, Connecticut. After studying journalism at the University of Missouri, he was press aide to both Secretary of the Navy John Warner and Chief of Naval Operations, Admiral Elmo Zumwalt Jr., during the Vietnam war.

Walton was one of the first 150 employees at CNN when the network launched in 1980. He was CNN's first chief White House correspondent, and also filed the first video reports from Moscow when Soviet hard-liners staged a coup against Mikhail Gorbachev in 1991.

"It was incredibly exciting, and by the time I was 40, I'd already had a 25 year career in journalism," he says. "I started to ask myself if I was going to do another 25 years. The business was starting to change, so I thought if I was going to do something different, it would be a good time to get started."

BABY STEPS

Walton started with some baby steps while still at the network. "Different groups would often invite me to speak on news-related topics. I'd ask if, instead, I could share with them some of the things I knew about leadership communication -- how successful leaders communicate to generate buy-in."

"Not only were they interested, but responded so enthusiastically to what I knew and shared with them, they asked if I could create executive educational programs in leadership communication. I couldn't do that while I was working as a full-time reporter," he says.

"But when the time came, in 1992, to decide whether to stay on at CNN for another three-year contract or attempt to turn what fascinated me into a business and livelihood, I took the plunge."

Walton was fascinated by the idea of building a consulting practice that would allow him to teach and coach executives and professionals about what he knew. He also liked the idea of writing and traveling on his own schedule, independent of a large organization. Twenty years later, he's taught leadership and communication for universities, corporations and government.

He hasn't looked back once at the high-energy news business he left behind.

"At heart, I will always be a journalist. But, in reinventing myself in my early 40s, I discovered that I had talents and skills in other areas -- including business -- that I hadn't previously been aware of."

(Editing by Beth Pinsker Gladstone, Bernadette Baum and Andrea Evans)