Alzheimer's disease: Here's another reason to hit the gym

According to a recent Swedish study, people with high blood-glucose levels (when you don't have enough insulin in your body) are 68 percent more likely to suffer from Alzheimer's disease later in life. They found that the high levels cause structural damage in the brain, leading to the disease.

The good news: Exercising for a half hour five times a week cuts your risk of developing high blood-glucose by 58 percent.