I quit smoking years ago, and I now hate the smell, and encourage people to stop smoking. Tobacco is very very bad for you. It can destroy your lungs, your heart, cause cancer and lost teeth.
Nicotine is NOT a sin. It may be a sin to mistreat your body with addictive substances, to ruin the magnificent creation that is our body. But nicotine is not a sin. Being mean to people is a sin.