As inhaling smoke into one's lungs is as foreign a thing to the body as anything, and it causes disease and death, and as we who know Christ are to take care of the temple where God dwells, it should definitely be considered that smoking cigarettes (tobacco, or any other substance) would be a behaviour that would rob God of His rightful dominion in that life, and over that one particular area of a carnal pleasure.
I once smoked between the ages of 18 and 28 (10 years, also!) and then quit. I also felt very guilty and would hide it from those I knew who were Christians...and that is because the Lord was convicting me about it.
1 Corinthians 6:19-20
Don’t you realize that your body is the temple of the Holy Spirit, who lives in you and was given to you by God? You do not belong to yourself, 20 for God bought you with a high price. So you must honor God with your body.
btw: Welcome to CFS!