I just think that exercise is an incredible supplimental tool to help achieve an overall improvement in lifestyle, health, weight and overall fitness. Look at it this way- If you needed to eliminate 1000 calories per day from your daily diet by only eating less, you would have to eliminate a prettly large portion of what you're used to eating. In terms of will power, this can be extremely difficult to maintain for very long. However, if you do an hour of moderate exercise every day (let's say 70% max hr on an exercise bike) you will burn 500-700 calories making the amount you have to cut out of your diet less. For some, that would be eliminating 2 large cokes. Much easier in my opinion and you get cardiovascular fittness as an added bonus.