I read and watched "Super Size Me" and it gave me some incentive to stop eating fast food and stop drinking soda. It helped that my friend also quit soda. You can do it. Slowly increase your mileage so your body can adapt to the mileage. There's no other way to do it than to ride and eat right.
I also cut out High Fructose Corn Syrup and Partially Hydrogenated Oils. Doing that narrows down what you can eat for a good diet. Mainly unprocessed foods.