People say exercise and everyone tends to think the gym. However this is total BS, you don't need to go to the gym to stay healthy, the only thing you need to do to stay healthy when eating lots of carbohydrates is to do an activity to burn them.
The other major misconception is people think thin=healthy when really all the 'healthy' (women especially) people on TV are definitely not healthy. In fact, unless you're very careful with a calorie restricted diet (lots of vitamins and enough protein to maintain your muscle tissue) you are doing significantly more damage to your body than if you were overweight.
It's been shown anorexia can shorten your life by 25 years. Being moderately obese (30-35 on the BMI) can take 2-4 years off your life and extremely obese (40-45) can take 8-10 years off your life expectancy. People who are in the overweight group don't see a reduction in life expectancy, unless they smoke.
Then it also depends on how healthy you are when you're obese. Many sportsmen and soldiers are obese to significantly obese, and I don't think you'll find a single one who's of normal weight. However, many of these men will live longer than the average normal weight person (assuming they don't use steroids), due simply to the fact that building muscle tissue usually helps build your heart tissue too, meaning you stand to live significantly longer.
That may be so when measured by BMI. That's a really crappy metric, since it holds muscle mass against you. That is, really developed count against you. And since muscle is much denser, it's as if they've got lots of fat.
IMHO, we'd be better tracking body fat %. Of course, even that's less-than-perfect. Subcutaneous fat may be unsightly, but it's not dangerous to health. It's the fat around your organs that's bad for you.
If you want to become diabetic, take some streptozotocin :)