My last real cigarette was in March I think and I did notice some health improvements very quickly. I never felt there was much wrong with my breathing anyway but what I did notice after a week or so was that I could do the deep breathing exercises in my yoga class without risking a coughing fit and my chest felt clear in the morning. On the bike, I used to feel a bit chesty for a few miles, then cough and my breathing would be fine but it's fine from the start now and no cough but I still can certainly make myself out of breath.
There is no doubt that my circulation began to improve within a day or two as I used to be very prone to cold hands and feet and a certain part of the male anatomy works much better now.
I'm not sure whether ti's a benefit of stopping smoking or just getting fitter but 3hr long Salsa classes used to make my leg muscles really burn but doesn't nowadays.
Perhaps it's just coincidence but I didn't have a single cold in 2014 whereas before I often got a cold at the start of winter which took forever to clear up completely.
I still sometimes think about smoking but have little desire to do so. The main trigger seems to be seeing the receptionist from the solicitor's office opposite my office window who often stands outside their door smoking and she is really rather pretty and I sometimes feel like popping a fag in my mouth and running over to ask her for a light and chatting her up
Then I remember she probably smells like an ashtray