I used to smoke. I started in early Highschool and continued for about 15 years. I stopped a few years ago and have only had a smoke or two with the occasional friend since when they are going through a rough time. Cold turkey. Actually bought a vape, but hated it. Many people say try to get yourself on those alternatives first. I say test if you are addicted to nicotine, I found that the easy one to beat. A couple of bad days, but I had tried before and knew what to expect. It's the social changes and the other things that bring it on.
It was drinking without smoking that was the hardest. I could do the coffee without smoking, but drinking was much more difficult. I had to stop hanging out with people who smoked and in bars which still allowed smoking inside. Fortunately, a few of us quit at the same time because the country was basically doubling the price and banning it everywhere which helped.
Try to hang around your friends who are anti-smoking and just explain to the smokers that you need a break for a week or two. I even had a friend who found reading a book about quitting smoking helped since eventually he found a few stories or examples that could work for him.
For me more than suppressing health, which improved but not exponentially, it was smells that I noticed. My smelling is so much better now. It's sort weird but crazy. I think smoking completely messed up my sense of smell and the foods I like sort of changed after, also I can no longer tolerate being in basements or places with poor ventilation and bad air pollution.