His habit was so strong that when told by doctors he might lose a leg, he saw it as a price worth paying to continue to smoke.
John, from California, thought nothing would help him give up. He tried numerous methods - gums, hypnosis, injections behind the ear costing $800 a time - but nothing worked.
Finally, he tried the anti-smoking pill, Zyban. He hasn't smoked now for seven years.
Mr Dodd told the BBC: "I had just about given up hope of finding anything that would be successful with me.
"I was motivated because they were going to cut my limbs off if I did not stop smoking.
"Although I was willing to give up a limb if I could have continued to smoke with impunity."
Mr Dodd said Zyban gave him a "millimetre of confidence" that he might be able to withstand the craving for tobacco.
"Zyban allowed me to outrun the hound of the Baskervilles for the first time in my life.
"Always before I had been caught. With Zyban I could just sprint a little harder, a little longer, a little better, but it was not a magic pill by any means - it required every bit of concentration and effort that I had ever mustered in my life."
Mr Dodd said he now felt much healthier. His blood pressure and cholesterol levels have dropped.
"I used to think I had to have a cigarette to live. I am surprised at how well I live without a cigarette.
"I could only walk about half a block at the time I stopped smoking, now my dog and I walk around three miles every morning.
"Not only has it improved my health, it has improved my social life as well. Friends that did not want to associate with me before are now back in my life. It has opened up a whole wealth of living for me."