I think learning to plan and monitor your behavior is the best way to learn to control and monitor your weight--otherwise, what will you "work harder" at?
You need to have a plan for both food and exercise: just having a vague intention to "work harder" and "make better choices" and "try to exercise" is basically a way to get all the misery of dieting with none of the results.
Here are a couple ideas:
1)Assign "points" to every "good" behavior: every day you eat on plan, every time you exercise. Keep a list of total points in a notebook you carry or on your phone. Once you reach some number of points, give yourself some amount of money.
2) Take a calendar (you can make one on the computer or on posterboard) and on each day, put "exercise" (or "E") and "Food" (or "F"). Add any other areas of behavior you are regulating--water intake or taking your vitamins or whatever. Get some stickers. At the end of the day, put a sticker over each behavior you were successful with: did you exercise? Did you eat properly? When you get to the end of the week or month, reward yourself based on how many stickers you have.