So there's this boy who loves tractors

He lived on a farm, and watched the tractors drive by all day. He subscribed to tractor magazines, collected tractor figurines, had loads of tractor posters on his wall and even had some DVDs of tractor documentaries. He lived his whole childhood loving tractors.
On his 17th birthday, his dad said to him "Son, you're finally old enough to drive, I think its time you had a spin on the old family tractor"
The boy was over the moon, and had watched his dad drive it so many times he didn't need lessons. He drove it around straight away and loved it!
Sadly, whilst driving it, he was involved in a nasty accident which damaged the tractor and put him in a coma for 1 year.
When he finally woke up, his parents were so relived. "Oh son, I can't believe you're back. We've been so worried about you but we never gave up hope! We even kept all your old tractor stuff and-"
"Dad, I'm sorry" The son interrupted "after what happened, tractors only remind me of the accident. I don't want to drive another tractor, see another tractor or even think about another tractor. I just can't"
Dad said "I understand, we'll sell all your old tractor stuff and never speak of it again"
So after selling all the merchandise, the son had quite a bit of money. The dad said to him "You know, you're finally 18, I think its time I took you to the local pub for your first legal pint". The son agreed that that would be nice.
When they arrive at the pub, they notice everyone is smoking cigarettes. The bartender is coughing as the dad orders the drinks. The son then goes up for the next round, and he notices the bartenders coughs.
"Does all this smoke bother you?" Said the son
"Yeah it really hits my lungs. I'll be happy once it's banned from the pub"
The son replied "Well I can help you with it no problem!"
The son takes a deep breath out, then breathes in all the cigarette smoke right into his lungs, and feels no pain doing it.
The bar tender is amazed! "Thank you, but how the hell did you manage that?"
The son replies "Did my dad not tell you...?"
"Tell me what?"
"I'm an ex-tractor fan!