Lisa Bell, Know Your Numbers

Millions of Americans resolved to lose weight in '08, so Know Your Numbers has an easy way to do just that.

In order to lose a pound a week, you will need to cut your daily calories by 500.

One pound equals 3,500 calories, so if you cut out about 500 calories between diet and exercise every day, you'll lose a pound a week. That is what is considered the best way for keeping weight off. 

That's not that much. Let's say you burn 250 calories by walking about 40 minutes. That only leaves you 250 calories left to burn.

To put it into perspective -- a 20-ounce bottle of soda has about 250 calories, or if you switch from mayo to mustard on your sandwich, you can save you 100 calories.

Those little changes can add up fast.