You've likely heard that it takes time for your stomach to signal the brain that you are full. That's why the experts advise that you slow down while you chow down.
One of the tricks you might employ is to start using chopsticks* while you eat, especially if you don't typically use them.
Another option is to use your non-dominant hand.
Either way, by doing things a little differently, you're getting the benefit of activating some new neural pathways.
*If you're looking for wooden chopsticks that are both a work of art and ergonomically designed, I'm sure that Maarten Meerman would be happy to discuss your requirements!