I understand what you are saying but an awful lot of people do have a choice. It takes some effort but lead healthier lifestyles. Teach your kids to plant a garden and cook healthier meals at home. Stop eating McDonalds, Burger King, or ordering out for pizza with such regularity. Stop buying cases of soda pop and allowing your kids to sit in front of the computer or video game for hours guzzling down soda. Exercise about 3-4 times a week. Planet Fitness is $10 per month, that's very affordable. Go outside and take a walk after dinner, it's free. Take your kids to the gym with you and teach them to exercise and workout. Take up swimming at the local park. You did touch on smoking...limit the amount of alcohol you consume, and don't use drugs. It takes some effort but it would go a long way towards making sure you are not suffering with diseases and other illnesses.
People pollute indiscriminately too. Stop throwing your trash by the roadside, walk it over to the nearest trash can. When your car is leaking oil, gas, or some other fluid repair it. Sure you might not be going out shopping or clubbing for a week or two but your environment will be cleaner. If you are going to save a few bucks and change your own oil or transmission fluid dispose of it properly, don't dump it down the nearest sewer or into the nearest river. There are things we can do to be healthier and have a cleaner environment but a lot of people are just lazy and irresponsible.