I prefer to think of all the good that will come of it rather than focus on what will be lost. There's no change without loss. There's a price for doing it and a price for not doing it and as an adult I get to choose.
I did a report in school a few years back about teenage smoking. The American Surgeon General Report (1994) stated that more people die from smoking related causes in one year than die of alcohol use, drug use, traffic accidents, suicides and A.I.D.S. (in America) combined. Over 400,000 per year. Non smokers that died of second hand smoke related causes came in at a paltry 50,000 per year. Granted the report is almost 10 years old and and many smokers have quit or died since then.
I quit 12 years ago and feel good about not having to worry as much about lung cancer and emphasema. I may still get it, but I won't have the sting of guilt knowing that I could've done something about it. I empathize with smokers' struggles and try to help whenever I can. Been there, done that. Smoke-free is a beautiful thing.