Tobacco legal yet causing far more illnesses and death than all other addicting drugs combined.
It kills in the UK alone about 328 people per day.
Tobacco is highly addictive and it can be quite hard to stop smoking, Helplines exist for all those who want to stop and a wide variety of Nicotine replacement products exist (Gum, inhalator, nasal sprays).
Tobacco really damages your health, your breathing ability and thus any physical performance. Do not be mistaken all the messages on the tobacco packs are absolutely right: tobacco kills, ruins your skin and lungs.