Seeing people drinking or smoking is not a problem for you. The problem is if you become alcoholic or smoker.
Because some people like to drink or smoke, it's not a problem for you. It's their problems.
I used to smoke a whole pack of cigarettes for 3 years. One week ago, I had an asthma attack (I couldn't breathe at all) My sister called an ambulance, I was in the hospital for 3 hours. Now, I have to take medications, and inhale oxigen. Doctors said this: You have to quit smoking, and you have to take medications; also inhale that oxigen thing for 1 or 2 months.
If I continue smoking, I'll damage more my lungs, and I could suffer from asthma for the rest of my life or my lungs could stop working, and I could die.
I think God told me to quit smoking.
Smoking or alcohol abuse is something stupid.