How can I get myself to stop over-eating and exercise more, like every day for half an hour, right?

Water, fiber. and vegetables. Try to eat at least 10 grams of fiber at the beginning of each meal. Get the fiber from vegetables, not grains. Supplement this with significant amounts of water. The water will expand the fiber in your stomach and will help you to feel fuller, sooner. Eat vegetables first, and meats later. Fill up on calorie-poor foods first, before calorie dense. .
Drink water before. Try drinking water and lemon before eating. Stop when she have a full feeling, not stuffed. Try a cardio work out 22 minutes per day or 11 minutes two times per day.
Therapy/Consultation. For many people the attempt to eat less and exercise more will not succeed without help. Seek out the services of counselors, e.g. Health psychologist and/or nutritionist, that can help you develop a long term plan and implement it. Also, if you can afford it, hire a personal trainer or go to a gym that provides one.