According to the calculator, if you're an average American you'll eat two pigs, two-thirds of a cow, and 289 chickens in the next ten years. If you reduce your meat consumption by even ten percent, that adds up to half a pig, a calf, and 29 chickens.
For the environment, what matters more than the lives of the animals is the resources used to produce them, including petroleum, water, and antibiotics.
The difference between a vegetarian diet and a meat-eating one, over ten years, is 18,000 pounds of carbon dioxide and 238,810 gallons of water. Think about California droughts and wildfires in that context.