One of the things that might grant you a long, healthy life is what you eat. And one of the healthiest diets is the vegetarian diet, where it has been proven that vegetarians experience lower rates of heart disease, less cancer and less health problems.
When being a vegetarian, you get all your body need from foods other than meat, and with balance and variety you will never feel the difference.
Just be sure to add a bit of fish into your diet, that then would be called a perfect diet.

You can add protein to your meal with out meat, use tofu or soy milk in your cereal. Whole grains, beans, seeds and nuts are rich protein sources as well.
Vitamin B12 is a very difficult nutrient to get without eating meat, you can get it from breakfast cereals or fortified soy products.
As for calcium, you can get it from spinach, broccoli, almonds and dairy products.
To avoid anemia you need iron, and that nutrient can be gotten from lentils, chickpeas, beans, spinach, bran flakes and dried fruits.
Zinc is also a very important mineral that strengthens you immune system, and your body can get that from pumpkin seeds, beans and cashews.