The key, Katz says, is constantly giving your brain new challenges. "These are not meant to make you into a supergenius," Katz says. "It's a mental fitness approach, not mental powerlifting."
The goal is to experience the world as a child does. "Kids use all of their sensory bandwidth," Katz says. "As adults, our daily life can be encrusted with routine."
1. Reroute Your Life: "One of the big things that we emphasize is doing rerouting activities in new ways," Katz says. Take a different route to work, for example. This forces your brain to pay attention to what its doing, and activates parts of the brain that are known to be involved in spatial navigation. The idea is to bring online new circuits, to actually form new associations. By increasing the range of stimuli, "you're increasing the bandwidth of your brain, essentially," Katz says.
2. Use a different sense to do a standard activity: Instead of looking for your keys, find them using your sense of touch. Figure out the correct change by feel rather than sight. In the morning, choose your wardrobe by matching textures rather than colors. ("Don't do this on a workday," Katz jokes.) Rearrange the things that you use routinely on your desk. The key: get yourself out of the routine. Your brain can easily get stuck in a rut, he says: "If you move your trashcan, you will be throwing paper onto the floor." According to Katz, humans tend to rely on sight and sound over other senses. When we use our other senses, this uses the brain in a new way.
3. Shop at a farmers' or ethnic market: Give yourself an opportunity to taste touch and smell the actual foods that you're going to buy. This not only gives you the chance to pick out new foods, but it emphasizes other senses besides sight: smell, touch, and taste. "Most of supermarket sales are designed to appeal to sense of sight," Katz says. "That's why they make tomatoes that are bright red, but have no flavor.
4. Hang Out: "One of the best stimuli is other people," Katz says. Have social interactions, and adjust the social interactions you already have. Change where people sit at the dinner table. "It changes your whole perspective, and changes the social dynamics," he says. Katz recommends taking up bridge, because the game is intellectually demanding, and much of that challenge involves interacting with other people. Studies show that older people with strong social networks tend to have less decline in cognitive ability. "Large parts of our brain are devoted to decoding other people," he says. "Nothing captivates the brain's attention like the presence of another human being."
5. Get some fresh air: "When you go and have a great hike, your brain feels invigorated. One I feel strongly about is that humans are very engaged with the natural world," says Katz. "The variety of brain stimuli that exist in the natural world is much greater and richer than the human-created world." He recommends taking up an activity that takes you outdoors: hiking, bicycling, or birdwatching. "My personal favorite is fly fishing," Katz says. "You have to pay attention to sounds, sights, temperature, insects, the wind, the currents, so many things."
6. Wing it: Take a random joy ride. Go out in the country. No map. Just close your eyes and point to a map. Try to get there. Don't take a planned route. Basically go exploring. The brain craves novelty. The more you provide new things, the more the brain works. "What the brain does is filter out the unchanging things to have more capacity to watch out for new things. Novelty perks up your attentional mechanisms," says Katz. "Routines are good. But they come at a price. If you have too routinized a life then you are depriving your brain of a certain stimulation. Middle-class American life, with its focus on predictability, has less of that novelty. These exercises are a way to artificially increase that."