"When I was a kid, we lived about three blocks from a bowling alley. I'd been initiated into the joys of duckpin bowling by my older brother, Alan (duckpins are the smaller pins found mostly at bowling alleys on the East Coast). Because the balls are also smaller, even children, given enough practice, can get really good at the sport.

"I lived to bowl, which is where most of my allowance went.

"As I grew older, bowling became less important, but unbeknownst to me, those narrow lanes had left corresponding grooves in my neural circuitry. Many years later, when I'd flatlined once again, Gordie and I happened to drive past a bowling alley. He turned the car around and pulled into the parking lot despite my protestations that I had too much to do and didn't like bowling anyway. However, the simple act of picking up a ball and rolling it down the alley reawakened youthful neural networks primed by possibility, and soon I was laughing and having the time of my life.

"You may not remember the joy you once felt in a hobby or activity that has fallen off your radar, so you may need to enlist a friend or loved one in helping you remember. One of my friends who is in her 70s was a dancer in her youth. During a flatline period of her own, she noticed a jazz dance class at her gym and signed up. It was as if a light switch were turned on inside her.

"In 1979, Harvard professor of psychology Ellen Langer conducted a fascinating study of how we can improve well-being by doing things we enjoyed in our younger years. She calls it her 'counterclockwise study,' and you can read more about it in her 2009 book, Counterclockwise: Mindful Health and the Power of Possibility. Langer and her colleagues invited two groups of men in their late 70s and early 80s to live in a meticulous re-creation of the year 1959 for one week each. They transformed an old monastery in Peterborough, New Hampshire, into a living time capsule of the world as it was 20 years earlier.

"One group was instructed to pretend that the year really was 1959 and talk about 'current' events like Castro's victory in Cuba and Nikita Khrushchev and the Cold War in the present tense. The other group spoke of events in the past tense more as observers than participants. All of the volunteers were tested physically and cognitively before the study began and again at its conclusion. While both groups showed increases in strength, flexibility, memory, and intelligence, the group who had acted as if it were really 1959 improved the most. Living like younger versions of themselves actually rejuvenated the men, demonstrating the profound effect that our thinking has on our body.

"Think back to a time before you were burned out — when you were at your prime and filled with enthusiasm for life's possibilities. What did you enjoy doing? Choose one activity (like bowling, for example), and put it on your calendar. This is an experiment. If it rejuvenates you, add it to your regular schedule. If it doesn't, choose another activity from an earlier time in your life. Make sure to get out your calendar and actually add this to your schedule."