In case you haven't been paying attention, exercise is awesome. It prevents obesity and cancer, improves cardiovascular health, stops you from shrinking so much in old age, and will combat those holiday pounds like nothing else will.

And now, as an added bonus, scientists have discovered that exercise also helps your brain. By stimulating the production of brain neurons in older adults, physical activity actually keeps the brain from shrinking in old age.

Previously, scientists had thought such production of new neurons was impossible. However, this recent research suggests that three hours of brisk walking per day can help seniors at risk of losing their independent functioning.

So get active!