AviLGh, I dont' want to sound like one of these "reformed smokers" that I hate to listen to, but here's one personal experience with it all.
You'll get a heads up during your yearly physical that you need to stop smoking big time when your red blood count comes back high. This is caused because your blood is trying to compensate for the lack of oxygen.
Zyban or Wellbuterin (did the wellbuterin plus the patch to quit at one time) made me feel pretty strange, no business in the cocpit. Since I"m only PPL I grounded myself for the duration of that mess. Plus on the FAA list of drugs not to take while piloting.
Now, there's the "it won't happen to me" attitude on the dangers etc. I had that feeling also, and unfortunately I've just had to deal with a session of surgery for oral cancer. Next up is the radiation and chemo. Fun. Comment from the doc during last follow up? "Wages of smoking" No **** sherlock.