By now, everyone knows that regular exercise and a well-balanced, low-fat diet are good for your body. But new evidence shows that Sudoku helps, too.

In a small study of people with mild memory problems, to be published this week in The American Journal of Geriatric Psychiatry, researchers found that those who combined exercise and a healthy diet with mental exercises and stress-reduction techniques showed "significant" improvements in their brain functions and metabolisms--even after just two weeks. Gary Small, director of the UCLA Center on Aging, and his colleagues compared brain scans of patients before and after, and found that, compared with those who maintained their normal routines, participants who adopted healthy habits were 5 percent more efficient in using the parts of the brain that control memory functions. Many also lost weight and lowered their blood pressures.

In his newly published book, "The Longevity Bible," Small elaborates on the healthy habits from the study, and adds four more, claiming they will not only help readers achieve healthier minds and bodies, but longer lives:

Sharpen your mind by doing exercises like crossword puzzles (and shutting off the TV).

Maintain a positive outlook (research shows it can actually boost the body's immune system).

Cultivate healthy and intimate relationships with friends and family.

Promote stress-free living through activities like yoga or meditation.

Master your environment by reducing clutter.

Get fit through cardiovascular conditioning and strength training.

Eat a healthy diet that includes antioxidant-rich fruits and vegetables, proteins and whole grains.

Ask your doctor about new drugs and treatments.

Small says that "simple everyday lifestyle choices have a major impact on how long and how well we live." So choose wisely.