There are many well known health problems associated with cigarette smoke, but there are also general lifestyles accompanied with it. Smokers are known to be more irritable than nonsmokers, and normally see more problems with sleep patterns. Anxiety is also more predominant in smokers than in their nonsmoking counterparts.
On a bodybuilding level, male smokers have been known to have higher estrogen and lower plasma-testosterone levels than nonsmokers do.
Smokers will claim that there are benefits to smoking, but there are none. Smoking cigarettes is no different than scratching a mosquito bite. Whatever pleasure is gained from it would not be there if the bite wasn't there to begin with! Cigarettes don't give you any pleasure above and beyond what you had as a nonsmoker. Its effects on your body in terms of possible health effects are plentiful. Top it off, the hormonal and metabolic effects of tobacco cause lack of mental and physical energy, endurance and recovery, and you will experience these problems in both your everyday life and in the gym.
Source: Health Canada