I smoked steadily from 1996-2011, probably started stealing cigarettes from my dad in 93-94, when i was 11 or 12, I was completely addicted, I smoked just under a pack a day. 2 packs when I got drunk.
I hit my breaking pint while I was out skating, I felt like my heart was going to explode.
I quit, started to immediately improve my cardiovascular health, pick your thing, run, bike, gym machines or whatever you want. My biggest advice is to go and take advantage of your new lung capacity, it makes the idea of going back fade faster.
I am cigarette free 9 years this summer.