I think willful sin maybe ignoring the holy spirit when being convicted. Just because you want to E,g, get your leg over etc. Or think yeah it's bad smoking, but I'm going to die anyway, so ignore and continue etc.
Brother, you seem to have the heart to change but can't because of temptation(emotions, cravings). You feel condemned and think that you're in a futile struggle to be free but, please, stop panicking/struggling/worrying for a moment and ask yourself why are you really worried? The battle is not in what you can and can't do. The battle is in your head. Every emotion and feeling are direct results of your thoughts.
Just as some have already pointed out, the battle for your addiction is already over. Jesus your savior has won it for you already. You just have to keep anchoring your faith on that truth and all those emotions will fade away.
You may think to yourself, "it's easier said than done" or "it's not as simple as that" but it is. For example, a guy gets really angry in a restaurant after getting a really bad service or whatever. It gets to the point that he starts asking for the people in charge of the restaurant, then suddenly the owner comes out and he recognizes that this owner is the same guy who saved his life a year ago. What do you think happened to all his emotions and rage? Gone. In an instant.
In the same way, stop struggling thinking about quitting smoking and worrying about how you are not winning, start by the truth (Jesus). Read verses that are life, love, and peace and avoid verses that are about good and evil, the law, and condemnation because all those Jesus overcame for you already.
Keep it simple brother. The more you worry about tomorrow, your smoking, and your addictions, the more you'll likely lose that day. By struggling to focus on doing good, you lose the peace and the joy of living a stress-free life.
If you're still unsure of your salvation, go back to the bible and read the verses that really talk about salvation. Don't get side-tracked on things you have doubts because that's where you'll likely be attacked.
"For God so loved the world that He gave His only begotten Son, that
whoever believes in Him should not perish but
have everlasting life. For
God did not send His Son into the world
to condemn the world, but that
the world through Him might be saved." John 3:16-17
Read that verse until that truth sinks in and let it continually renew your mind daily. The more you focus on Jesus, what He did for you, and all the things you have now because of His work, the more things that are lesser will fade away. And before you know it, you are producing good works, at peace, joyful, healthy, and winning.
God bless you and may God's grace fill you with peace and security every single day of your life.
