If you're a heavy smoker, there are many, many effects from the nicotine you live on that can damage your body.
So, the question is how does one undo the effects caused by smoking? Well, the best solution would be to quit smoking and start over.
First, you would see that your body would react both physically and psychologically as you undergo withdrawal symptoms, but keep in mind that this would last for a short time period and you would be able to lead a healthier life after that.
To undo the effects of smoking, make sure you have a solid nutrition plan.
As the saying goes, you are what you, eat so eat healthy.
Good food can help boost your systems and help clear the toxins from your body.
Instead of indulging in alcoholic substances and fatty foods, learn to follow the food pyramid and have a balanced diet.
This would also decrease the chances of getting a stroke or heart disease.
Aside from that, figure out a complete workout regime.
In order to achieve the maximum benefits of a fit body; you would need to do more than light weights and an evening jog.
Take the effort to hit the gym and get tips from a trainer.
To counter act all the effects smoking may have caused, take part in exercises that work all planes of motion, stretching, foam rolling, interval training, and static holds along with correct breathing.
It's not impossible to reverse the effects of smoking; it just takes a whole lot of willpower and dedication.
So, don't give up and keep trying.