I've been a vegetarian since about age 8. To start off with, I just didn't like the taste of lamb, and pork. I used to eat beef, but after watching way toooooo many animal/vet shows I just gave up on meat altogether.
Sometimes I miss beef sausages, and chicken but I just find other tasty things to eat.
Its really important to have variety in your diet as a vegetarian. I found that if I just stuck with plain salad, I'd miss chicken more, so mix it up!
And just because you're a vego, doesn't mean pig pig pig out on the junk food.
Nuts I find are a great source of protein, and they are also a great snack, and provide a slow release of energy unlike sugar coated junk foods. Pasta is a great vegetarian food too! Its filling and delicious and if you make it yourself, you can stuff it with whatever you want.
And I hate to say this, but anything green is good! Spinach, walnut and mango salad is a really good summer lunch. I'll have to find the recipe and post it.
Fresh is also best. So fruits, veges, nuts, legumes are all your friends.
Good luck with being a vegetarian, its hard sometimes but you just gotta get through it.