I work out regularly -- power walking, aerobics, weight lifting, yoga. But none of these have exhausted me as thoroughly as my first year sitting in a college classroom as a "nontraditional" (aka "old") student. By the end of each day of classes, I felt like I'd run a 10K carrying two toddlers and a week's worth of groceries.
That's not surprising, says Duke University neurobiologist Lawrence Katz. "The brain uses an enormous amount of the body's energy," he says. "Even under normal circumstances, it uses about 20 percent of your body's entire energy production. When you work your brain harder, you use more. The blood flow goes to the brain, and it's really like working out."
The good news is that by my sophomore year, exhaustion was replaced by exhilaration -- comparable, perhaps, to an athlete's being "in the zone."
Going to college is on the power-lifting level of brain exercise, but the more researchers learn about the brain -- and this is "the century of the brain," says Sandra Chapman, executive director of the Center for BrainHealth and a professor of behavior and brain science at the University of Texas at Dallas -- the more they stress the power we each hold to keep our brains fit throughout our lives.
One myth brain researchers want badly to debunk is the idea that the brain is "an untouchable black box," says Chapman. Rather, she says, "The brain is highly modifiable by everything we do." And, says Katz, the adage that after age 30 we lose 100,000 brain cells daily is just another depressing myth.
"Basically, the human brain remains intact until very late in life," he says. "What does happen is that the richness of the connections between cells begins to decline."
Granted, as with a lot of things, we lose speed as we age.
"As people get older, they learn more slowly," says Guy McKhann, professor of neurology at Johns Hopkins University and co-author of Keep Your Brain Young: The Complete Guide to Physical and Emotional Health and Longevity. "But once they get it, they keep it as well as younger people."
Teaching your brain new tricks is like a workout for the mind. It's never too early to start, and you don't have to ante up tuition to start your brain fitness program.
Warm-ups: In his book Keep Your Brain Alive, Katz suggests simple ways to stimulate new neural connections within the brain, including brushing your teeth with your non-dominant hand and taking a new route to work.
"Do routine things in a non-routine way to use new pathways in the brain," he says. "This can lead to greater flexibility and agility in the brain. Rearrange your desk. Put your telephone or wastebasket in a different place. You will be amazed, if you move your wastebasket, how long you'll throw paper on the floor."
Social interactions also appear to benefit the brain. When you have time, skip the self-service gas pump or bank ATM and conduct your transaction with a person instead.
"These interactions are unpredictable," Katz says. "Because so many parts of our brains are evolved to respond to other human beings, social interaction stimulates large parts of the brain."
Travel, too, provides new experiences that create new neural pathways, especially if you step out of your chain hotel.
Katz concedes these theories work backwards from the observation that strong social connections and active lives correlate with better cognitive functioning in older people. And even novice researchers can tell you that correlation does not mean causation.
But Katz is convinced the connection works two ways: Better brain function causes more active lives and richer social networks, and people with active lives and rich social networks maintain better brain function.
Aerobics: You may have heard that working crossword puzzles is good exercise for the brain, and that's true -- for the crossword-puzzle-working parts of the brain. If you enjoy crossword puzzles, have at it. Indulging in activities that work the brain always is great exercise, and choosing an activity you love -- be it doing crossword puzzles, playing the piano, or writing poetry -- will keep you engaged.
"Whatever you spend time doing is what part of your brain is going to strengthen," says Chapman. "Don't do random things. Ask yourself if that's the part of your brain you want to build." In her work with stroke patients, Chapman notes, "We see people who lose a lot of their ability, but the first thing to come back is the thing that they did the most."
To keep building brain strength, you must keep reaching for new skill levels. Brain imaging reveals that learning uses large portions of the brain. "Once you've gained expertise in that skill, less of the brain lights up [when you do it]," says Chapman.
Power lifting: Going to college, learning a language, taking up Japanese calligraphy -- these sorts of things are the power lifting of brain exercise.
Just as you don't want to try hoisting 200 pounds your first day in the gym, however, you must allow yourself time to master a new challenge, says Chapman. "You can get better at anything, but it's important to give your brain time and practice."
Exercising higher-level, big-picture thinking is another form of power lifting. "Read a paragraph and in one sentence, give me the higher-level meaning," suggests Chapman. "Abstract it. That requires a lot of brain power, using world knowledge, using text information. It's pulling in all your resources."
Stretching and cool-down: Jeffrey Schwartz is a research professor of psychiatry at UCLA's Neuropsychiatric Institute. Schwartz, whose specialty is the research and treatment of people with obsessive-compulsive disorder, advocates mindful breathing for controlling out-of-control worrying as well as for relaxation.
"The key, really, is the refocusing," he says. "When you refocus, you activate alternative brain machinery."
Sitting quietly and focusing your attention on the in and out of your breathing "really is like going to the gym; you're strengthening your brain," says Schwartz. "When you stop doing it, you have a stronger brain."
Schwartz describes mindful breathing techniques in his book, Dear Patrick: Life is Tough -- Here's Some Good Advice, but cautions that it takes more strength than it appears to. He recommends 20 minutes of the meditation technique, but says, "Not everyone gets up this point."
For a cool-down from the day that benefits the brain, turn off the TV and relax with a book instead. Reading is far better for keeping the brain on its toes.
"Reading is a very complex process, when you stop to think about it," says McKhann. "You have to recognize the letters and the words they make, you have sentence structure, you have to take this input information -- which is all being brought in visually -- and relate it to what your brain already knows. It's an awful lot of cross-talk in the brain."
If you must turn on the set, feed your brain "thinking TV" such as history documentaries, in which you must incorporate new information, instead of just empty entertainment.
And remember, these researchers stress, you're never too young to start a fitness program for the mind. Developing good brain habits early can keep your brain in shape well into your later years -- and vice versa, when it comes to bad brain habits.
"Habits are increasingly hard to break as you get older," says Katz.
So use it before you lose it.
Sophia Dembling is the author of The Making of Dr. Phil.