When I was working, I could eat anything I wanted and as much as I wanted without gaining weight. Just before I retired, I bought a treadmill to use in the winter. I also cut a lot of firewood and hike and hunt in the woods. Since I wasn't burning calories like I was on the big brown truck, I also started eating less at meals and often only eat fruit or vegetables for lunch.
Get out of bad habits too. I found myself getting on the computer late at night and automatically going for a snack. I was gaining weight and suddenly realized that I wasn't hungry when I was doing this-it just beacame a habit. Leaving the table before you feel full helps as well.