"Kaizen" is a Japanese word that means "improvement" or "good change."

It's also the name of a philosophy focused on making small changes that boost performance from top to bottom in business (Toyota follows it) as well as in personal well-being.

But can kaizen apply to brain health too?

Researchers at the University of California and the University of Tsukuba in Japan wanted to see if they could measure immediate improvements in the brain from small, positive steps.

Their study, published in the Proceedings of the National Academy of Sciences, included 36 young, healthy adults performing 10 minutes of yoga or tai chi. Afterward, the participants underwent a brain MRI scan.

That small amount of physical activity created measurable changes in the part of the brain involved in laying down memories (the hippocampus) and in another that handles detailed memory processing.

A recall test also found that participants had improved memory performance.

That's good news if you're one of the 77 percent of American adults who don't meet minimum guidelines for aerobic and strength-building activities.

It shows that you can build up your activity level by making one good — small — change at a time, and still reap immediate improvements in your brain health along as well as upping your chances of getting a good night's sleep and managing stress.

Start with 10 minutes of yoga or walking daily. You'll become sharper, smarter, and a whole lot less stiff.

Then set your sights on increasing the time to 30 to 60 minutes a day, one step at a time.