Eat three square meals a day, skip on snacking (unless it's something healthy like carrot sticks). Every time you want to snack do 20 push ups and/or sit ups. Drink a lot of water. Exercise at least 3 times a week for an hour each time (jogging, biking, walking (outside of your job and regular tasks) . Don't grocery shop when your hungry. During your tv show commercials do stretching or sit ups or push ups.
By eating healthier and exercising a lot more. Also, don't focus on NOT eating unhealthy foods; it's extremely important that you indulge once in a while. About 2-3 times a week of indulging on small foods (maybe a cookie or so) is very healthy. It releases a lot of stress on your heart. Um, yeah you exercise a lot more and you do things differently than you used to. Don't do the same things you've been doing every day.