I used to be really into salads with all the veggies cut up small. I'd add shredded carrots, finely chopped celery, and itty bitty bits of diced red pepper. If you're used to doing the same thing, switch it up and go for a chunky salad instead. Chop up carrots, cucumbers, zucchini, tomatoes, apples, and whatever else you love into big pieces.
Not only will it take less time to prepare your salad, but chomping down on big pieces of veggies requires more chewing and more effort. That means it will take longer to eat your salad, and you'll end up feeling more satisfied, which translates to eating less food afterward.