If you're not exercising now, then adding exercise can be a big benefit as long as you don't increase your food intake to offset your exercise. I use a rowing machine 20 minutes a day three days a week. I try to exercise at least two more days a week by walking or doing yard work (shoveling two and half feet of snow this weekend gave me all the exercise I needed). If you row flat out you can burn a lot of calories (1000 calories per hour) - the rowing machine is one of the main exercises used by Crossfit people (of which I am not one).
In addition simply eating less food can be huge. I recommend the free online book "Hackers Diet" (LINK) which I think is full of great practical advice. I realized after reading it that I was eating more food than I really wanted - and cut out a lot of mindless eating I was doing like nuts between meals and larger meal portions than I needed. I did NOT change the diet I was eating or cut out any food types - I just became more aware of what I was eating so I wouldn't eat on automatic pilot. The book also includes an exercise plan - worth a try if you don't have a health club or any equipment available (it's all stuff you can do in your home while listening to music).