I smoked for the best part of 18 years and in that time managed a 3.15 marathon and sub 20 parkrun, Sure someone will say "what time would you have got if you didn't smoke", maybe i wouldn't have run...who knows.....i'd smoke before and i'd smoke after, not big or clever just something i did. Gave up three years ago and wouldn't go back now. Loads of footage of sports stars of the 60's, 70's and 80's smoking, same as drinking, woudn't happen now but some may say the cocktail of chemicals that sportstars take now may be just as bad in the future.